A comprehensive review of search engine relevancy algorithms. While some of the general details have changed, the major themes referenced in this article were still relevant when I reviewed it a year after publishing it.

Why Did I Write This Article?

Many people think a search engine is broken or their site is banned if they do not rank in one engine while they rank great in others. This article will hopefully help searchers

understand the different relevancy criteria used by different engines. While people have looked at search engine ranking factors on a global level I do not think anyone has spent much time comparing and contrasting how different search engines compute their relevancy scores or bias their algorithms.

I think one of the hardest parts of explaining SEO is that the web is such a diverse place where things that make sense in one industry would make no sense in another industry. In addition, different engines look for different things to determine search relevancy.

Things that help you rank in one engine could preclude you from ranking in another.

There is enough traffic out there that it might make sense to do ultra aggressive SEO on one burnable site for quick rankings in MSN and Yahoo! while spending time using slow growth long term low risk techniques on a site you eventually want to rank in Google.

I thought it would be worth compiling notes comparing how relevancy is defined by each engine (or how I perceive it based on my experiences). This page makes no aim to be comprehensive, but is designed more for making it easy for people new to the web to

understand the differences between the different engines.

Bias is Universal. The Definition of Relevancy is Not.

Each major large scale search engine is ran by a large corporation. Each of these corporations is a for profit entity which has their own underlying principals or core beliefs which helps guide how they craft the search relevancy. While some machines automatically evolve search relevancy via genetic algorithms each major search engine still has some human input in how relevancy is calculated (at the very least humans write some of the algorithms).

The Bias of this Article

Originally when I started writing this article I wanted it to be more about search relevancy perhaps from more of an academic type standpoint, but my perspective on search is as one who understands it more from a marketing perspective.

The Short Version

Yahoo!

• been in the search game for many years.
• is better than MSN but nowhere near as good as Google at determining if a link is a natural citation or not.
• has a ton of internal content and a paid inclusion program. both of which give them incentive to bias search results toward commercial results
• things like cheesy off topic reciprocal links still work great in Yahoo!

Google

• has been in the search game a long time, and saw the web graph when it is much cleaner than the current web graph
• is much better than the other engines at determining if a link is a true editorial citation or an artificial link
• looks for natural link growth over time
• heavily biases search results toward informational resources
• trusts old sites way too much
• a page on a site or subdomain of a site with significant age or link related trust can rank much better than it should, even with no external citations
• they have aggressive duplicate content filters that filter out many pages with similar content
• if a page is obviously focused on a term they may filter the document out for that term. on page variation and link anchor text variation are important. a page with a single reference or a few references of a modifier will frequently outrank pages that are heavily focused on a search phrase containing that modifier
• crawl depth determined not only by link quantity, but also link quality. Excessive low quality links may make your site less likely to be crawled deep or even included in the index.
• things like cheesy off topic reciprocal links are generally ineffective in Google when you consider the associated opportunity cost

Ask    

• looks at topical communities
• due to their heavy emphasis on topical communities they are slow to rank sites until they are heavily cited from within their topical community
• due to their limited market share they probably are not worth paying much attention to unless you are in a vertical where they have a strong brand that drives significant search traffic

The long version…

Yahoo! Search

Yahoo! was founded in 1994 by David Filo and Jerry Yang as a directory of websites. For many years they outsourced their search service to other providers, but by the end of 2002 they realized the importance and value of search and started aggressively acquiring search companies.

Overture purchased AllTheWeb and AltaVista. Yahoo! purchased Inktomi (in December 2002) and then consumed Overture (in July of 2003), and combined the technologies from the various search companies they bought to make a new search engine. Yahoo! dumped Google in favor of their own in house technology on February 17th, 2004.

Yahoo! has a cool Netrospective of their first 10 years, and Bill Slawski posted a list of many of the companies Yahoo! consumed since Overture.

On Page Content

Yahoo! offers a paid inclusion program, so when Yahoo! Search users click on high ranked paid inclusion results in the organic search results Yahoo! profits. In part to make it easy for paid inclusion participants to rank, I believe Yahoo! places greater weight on on-the-page content than a search engine like Google does.

Being the #1 content destination site on the web, Yahoo! has a boatload of their own content which they frequently reference in the search results. Since they have so much of their own content and make money from some commercial organic search results it might make sense for them to bias their search results a bit toward commercial websites.

Using descriptive page titles and page content goes a long way in Yahoo!

In my opinion their results seem to be biased more toward commerce than informational sites, when compared with Google.

Crawling

Yahoo! is pretty good at crawling sites deeply so long as they have sufficient link popularity to get all their pages indexed. One note of caution is that Yahoo! may not want to deeply index sites with many variables in the URL string, especially since

• Yahoo! already has a boatload of their own content they would like to promote (including verticals like Yahoo! Shopping)
• Yahoo! offers paid inclusion, which can help Yahoo! increase revenue by charging merchants to index some of their deep database contents.

You can use Yahoo! Site Explorer to see how well they are indexing your site and which sites link at your site.

Query Processing

Certain words in a search query are better at defining the goals of the searcher. If you search Yahoo! for something like “how to SEO ” many of the top ranked results will have “how to” and “SEO” in the page titles, which might indicate that Yahoo! puts quite a bit of weight even on common words that occur in the search query.

Yahoo! seems to be more about text matching when compared to Google, which seems to be more about concept matching.

Link Reputation

Yahoo! is still fairly easy to manipulate using low to mid quality links and somewhat to aggressively focused anchor text. Rand Fishken recently posted about many Technorati pages ranking well for their core terms in Yahoo!. Those pages primarily have the exact same anchor text in almost all of the links pointing at them.

Sites with the trust score of Technorati may be able to get away with more unnatural patterns than most webmasters can, but I have seen sites flamethrown with poorly mixed anchor text on low quality links, only to see the sites rank pretty well in Yahoo! quickly.

Page vs Site

A few years ago at a Search Engine Strategies conference Jon Glick stated that Yahoo! looked at both links to a page and links to a site when determining the relevancy of a page. Pages on newer sites can still rank well even if their associated domain does not have much trust built up yet so long as they have some descriptive inbound links.

Site Age

Yahoo! may place some weight on older sites, but the effect is nowhere near as pronounced as the effect in Google’s SERPs.

It is not unreasonable for new sites to rank in Yahoo! in as little as 2 or 3 months.

Paid Search

Yahoo! prices their ads in an open auction, with the highest bidder ranking the highest. By early 2007 they aim to make Yahoo! Search Marketing more of a closed system which factors in clickthrough rate (and other algorithmic factors) into their ad ranking algorithm.

Yahoo! also offers a paid inclusion program which charges a flat rate per click to list your site in Yahoo!’s organic search results.

Yahoo! also offers a contextual ad network. The Yahoo! Publisher program does not have the depth that Google’s ad system has, and they seem to be trying to make up for that by biasing their targeting to more expensive ads, which generally causes their syndicated ads to have a higher click cost but lower average clickthrough rate.

Editorial

Yahoo! has many editorial elements to their search product. When a person pays for Yahoo! Search Submit that content is reviewed to ensure it matches Yahoo!’s quality guidelines. Sites submitted to the Yahoo! Directory are reviewed for quality as well.

In addition to those two forms of paid reviews, Yahoo! also frequently reviews their search results in many industries. For competitive search queries some of the top search results may be hand coded. If you search for Viagra, for example, the top 5 listings looked useful, and then I had to scroll down to #82 before I found another result that wasn’t spammy.

Yahoo! also manually reviews some of the spammy categories somewhat frequently and then reviews other samples of their index. Sometimes you will see a referral like corp.yahoo-inc.com/project/health-blogs/keepers if they reviewed your site and rated it well.

Sites which have been editorially reviewed and were of decent quality may be given a small boost in relevancy score. Sites which were reviewed and are of poor quality may be demoted in relevancy or removed from the search index.

Yahoo! has published their content quality guidelines. Some sites that are filtered out of search results by automated algorithms may return if the site cleans up the associated problems, but typically if any engine manually reviews your site and removes it for spamming you have to clean it up and then plead your case. You can request to have your domain evaluated for re-inclusion using this form.

Social Aspects

Yahoo! firmly believes in the human aspect of search. They paid many millions of dollars to buy Del.icio.us, a social bookmarking site. They also have a similar product native to Yahoo! called My Yahoo!

Yahoo! has also pushed a question answering service called Yahoo! Answers which they heavily promote in their search results and throughout their network. Yahoo! Answers allows anyone to ask or answer questions. Yahoo! is also trying to mix amateur content from Yahoo! Answers with professionally sourced content in verticals such as Yahoo! Tech.

Yahoo! SEO Tools

Yahoo! has a number of useful SEO tools.

• Overture Keyword Selector Tool - shows prior month search volumes across Yahoo! and their search network.
• Overture View Bids Tool - displays the top ads and bid prices by keyword in the Yahoo! Search Marketing ad network.
• Yahoo! Site Explorer - shows which pages Yahoo! has indexed from a site and which pages they know of that link at pages on your site.
• Yahoo! Mindset - shows you how Yahoo! can bias search results more toward informational or commercial search results.
• Yahoo! Advanced Search Page - makes it easy to look for .edu and .gov backlinks
  • while doing link:http://www.site.com/page.html searches (links to an individual page)
  • while doing linkdomain:www.site.com/ searches (links to any page on a particular domain)
• Yahoo! Buzz - shows current popular searches

Yahoo! Business Perspectives

Being the largest content site on the web makes Yahoo! run into some inefficiency issues due to being a large internal customer. For example, Yahoo! Shopping was a large link buyer for a period of time while Yahoo! Search pushed that they didn’t agree with link buying. Offering paid inclusion and having so much internal content makes it make sense for Yahoo! to have a somewhat commercial bias to their search results.

They believe strongly in the human and social aspects of search, pushing products like Yahoo! Answers and My Yahoo!.

I think Yahoo!’s biggest weakness is the diverse set of things that they do. In many fields they not only have internal customers, but in some fields they have product duplication, like with Yahoo! My Web and Del.icio.us.

Search Marketing Perspective

I believe if you do standard textbook SEO practices and actively build quality links it is reasonable to expect to be able to rank well in Yahoo! within 2 or 3 months. If you are trying to rank for highly spammed keyword phrases keep in mind that the top 5 or so results may be editorially selected, but if you use longer tail search queries or look beyond the top 5 for highly profitable terms you can see that many people are indeed still spamming them to bits.

As Yahoo! pushes more of their vertical offerings it may make sense to give your site and brand additional exposure to Yahoo!’s traffic by doing things like providing a few authoritative answers to topically relevant questions on Yahoo! Answers.

Google

Google sprang out of a Stanford research project to find authoritative link sources on the web. In January of 1996 Larry Page and Sergey Brin began working on BackRub (what a horrible name, eh?)

After they tried shopping the Google search technology to no avail they decided to set up their own search company. Within a few years of forming the company they won distribution partnerships with AOL and Yahoo! that helped build their brand as the industry leader in search. Traditionally search was viewed as a loss leader

Despite the dotcom fever of the day, they had little interest in building a company of their own around the technology they had developed.

Among those they called on was friend and Yahoo! founder David Filo. Filo agreed that their technology was solid, but encouraged Larry and Sergey to grow the service themselves by starting a search engine company. “When it’s fully developed and scalable,” he told them, “let’s talk again.” Others were less interested in Google, as it was now known. One portal CEO told them, “As long as we’re 80 percent as good as our competitors, that’s good enough. Our users don’t really care about search.”

Google did not have a profitable business model until the third iteration of their popular AdWords advertising program in February of 2002, and was worth over 100 billion dollars by the end of 2005.

On Page Content

If a phrase is obviously targeted (ie: the exact same phrase is in most of the following location: in most of your inbound links, internal links, at the start of your page title, at the beginning of your first page header, etc.) then Google may filter the document out of the search results for that phrase. Other search engines may have similar algorithms, but if they do those algorithms are not as sophisticated or aggressively deployed as those used by Google.

Google is scanning millions of books, which should help them create an algorithm that is pretty good at differentiating real text patterns from spammy manipulative text (although I have seen many garbage content cloaked pages ranking well in Google, especially for 3 and 4 word search queries).

You need to write naturally and make your copy look more like a news article than a heavily SEOed page if you want to rank well in Google. Sometimes using less occurrences of the phrase you want to rank for will be better than using more.

You also want to sprinkle modifiers and semantically related text in your pages that you want to rank well in Google.

Some of Google’s content filters may look at pages on a page by page basis while others may look across a site or a section of a site to see how similar different pages on the same site are. If many pages are exceptionally similar to content on your own site or content on other sites Google may be less willing to crawl those pages and may throw them into their supplemental index. Pages in the supplemental index rarely rank well, since generally they are trusted far less than pages in the regular search index.

Duplicate content detection is not just based on some magical percentage of similar content on a page, but is based on a variety of factors. Both Bill Slawski and Todd Malicoat offer great posts about duplicate content detection. This shingles PDF explains some duplicate content detection techniques.

I wrote a blog post about natural SEO copywriting which expounds on the points of writing unique natural content that will rank well in Google.

Crawling

While Google is more efficient at crawling than competing engines, it appears as though with Google’s BigDaddy update they are looking at both inbound and outbound link quality to help set crawl priority, crawl depth, and weather or not a site even gets crawled at all. To quote Matt Cutts:

The sites that fit “no pages in Bigdaddy” criteria were sites where our algorithms had very low trust in the inlinks or the outlinks of that site. Examples that might cause that include excessive reciprocal links, linking to spammy neighborhoods on the web, or link buying/selling.

In the past crawl depth was generally a function of PageRank (PageRank is a measure of link equity - and the more of it you had the better you would get indexed), but now adding in this crawl penalty for having an excessive portion of your inbound or outbound links pointing into low quality parts of the web creates an added cost which makes dealing in spammy low quality links far less appealing for those who want to rank in Google.

Query Processing

While I mentioned above that Yahoo! seemed to have a bit of a bias toward commercial search results it is also worth noting that Google’s organic search results are heavily biased toward informational websites and web pages.

Google is much better than Yahoo! or MSN at determining the true intent of a query and trying to match that instead of doing direct text matching. Common words like how to may be significantly deweighted compared to other terms in the search query that provide a better discrimination value.

Google and some of the other major search engines may try to answer many common related questions to the concept being searched for. For example, in a given set of search results you may see any of the following:

• a relevant .gov and/or .edu document
• a recent news article about the topic
• a page from a well known directory such as DMOZ or the Yahoo! Directory
• a page from the Wikipedia
• an archived page from an authority site about the topic
• the authoritative document about the history of the field and recent changes
• a smaller hyper focused authority site on the topic
• a PDF report on the topic
• a relevant Amazon, eBay, or shopping comparison page on the topic
• one of the most well branded and well known niche retailers catering to that market
• product manufacturer or wholesaler sites
• a blog post / review from a popular community or blog site about a slightly broader field

Some of the top results may answer specific relevant queries or be hard to beat, while others might be easy to compete with. You just have to think of how and why each result was chosen to be in the top 10 to learn which one you will be competing against and which ones may perhaps fall away over time.

Link Reputation

PageRank is a weighted measure of link popularity, but Google’s search algorithms have moved far beyond just looking at PageRank.

As mentioned above, gaining an excessive number of low quality links may hurt your ability to get indexed in Google, so stay away from known spammy link exchange hubs and other sources of junk links. I still sometimes get a few junk links, but I make sure that I try to offset any junky link by getting a greater number of good links.

If your site ranks well some garbage automated links will end up linking to you weather you like it or not. Don’t worry about those links, just worry about trying to get a few real high quality editorial links.

Google is much better at being able to determine the difference between real editorial citations and low quality, spammy, bought, or artificial links.

When determining link reputation Google (and other engines) may look at

• link age
• rate of link acquisition
• anchor text diversity
• deep link ratio
• link source quality (based on who links to them and who else they link at)
• weather links are editorial citations in real content (or if they are on spammy pages or near other obviously non-editorial links)
• does anybody actually click on the link?

It is generally believed that .edu and .gov links are trusted highly in Google because they are generally harder to influence than the average .com link, but keep in mind that there are some junky .edu links too (I have seen stuff like .edu casino link exchange directories). While the TrustRank research paper had some names from Yahoo! on it, I think it is worth reading the TrustRank research paper (PDF) and the link spam mass estimation paper (PDF), or at least my condensed version of them here and here understand how Google is looking at links.

When getting links for Google it is best to look in virgin lands that have not been combed over heavily by other SEOs. Either get real editorial citations or get citations from quality sites that have not yet been abused by others. Google may strip the ability to pass link authority (even from quality sites) if those sites are known obvious link sellers or other types of link manipulators. Make sure you mix up your anchor text and get some links with semantically related text.

Google likely collects usage data via Google search, Google Analytics, Google AdWords, Google AdSense, Google news, Google accounts, Google notebook, Google calendar, Google talk, Google’s feed reader, Google search history annotations, and Gmail. They also created a Firefox browser bookmark synch tool, an anti-phishing tool which is built into Firefox and have relationships with the Opera (another web browser company). Most likely they can lay some of this data over the top of the link graph to record a corroborating source of the legitimacy of the linkage data. Other search engines may also look at usage data.

Page vs Site

Sites need to earn a certain amount of trust before they can rank for competitive search queries in Google. If you put up a new page on a new site and expect it to rank right away for competitive terms you are probably going to be disappointed.

If you put that exact same content on an old trusted domain and link to it from another page on that domain it can leverage the domain trust to quickly rank and bypass the concept many people call the Google Sandbox.

Many people have been exploiting this algorithmic hole by throwing up spammy subdomains on free hosting sites or other authoritative sites that allow users to sign up for a cheap or free publishing account. This is polluting Google’s SERPs pretty bad, so they are going to have to make some major changes on this front pretty soon.

Site Age

Google filed a patent about information retrieval based on historical data which stated many of the things they may look for when determining how much to trust a site. Many of the things I mentioned in the link section above are relevant to the site age related trust (ie: to be well trusted due to site age you need to have at least some link trust score and some age score).

I have seen some old sites with exclusively low quality links rank well in Google based primarily on their site age, but if a site is old AND has powerful links it can go a long way to helping you rank just about any page you write (so long as you write it fairly naturally).

Older trusted sites may also be given a pass on many things that would cause newer lesser trusted sites to be demoted or de-indexed.

The Google Sandbox is a concept many SEOs mention frequently. The idea of the ‘box is that new sites that should be relevant struggle to rank for some queries they would be expected to rank for. While some people have debunked the existence of the sandbox as garbage, Google’s Matt Cutts said in an interview that they did not intentionally create the sandbox effect, but that it was created as a side effect of their algorithms:

“I think a lot of what’s perceived as the sandbox is artefacts where, in our indexing, some data may take longer to be computed than other data.”

Paid Search

Google AdWords factors in max bid price and clickthrough rate into their ad algorithm. In addition they automate reviewing landing page quality to use that as another factor in their ad relevancy algorithm to reduce the amount of arbitrage and other noisy signals in the AdWords program.

The Google AdSense program is an extension of Google AdWords which offers a vast ad network across many content websites that distribute contextually relevant Google ads. These ads are sold on a cost per click or flat rate CPM basis.

Editorial

Google is known to be far more aggressive with their filters and algorithms than the other search engines are. They are known to throw the baby out with the bath water quite often. They flat out despise relevancy manipulation, and have shown they are willing to trade some short term relevancy if it guides people along toward making higher quality content.

Short term if your site is filtered out of the results during an update it may be worth looking into common footprints of sites that were hurt in that update, but it is probably not worth changing your site structure and content format over one update if you are creating true value add content that is aimed at your customer base. Sometimes Google goes too far with their filters and then adjusts them back.

Google published their official webmaster guidelines and their thoughts on SEO. Matt Cutts is also known to publish SEO tips on his personal blog. Keep in mind that Matt’s job as Google’s search quality leader may bias his perspective a bit.

A site by the name of Search Bistro uncovered a couple internal Google documents which have been used to teach remote quality raters what to look for when evaluating search quality since at least 2003

• Google Spam Recognition Guide for Raters (doc) - discusses the types of sites Google considers spam. Generally sites which do not add any direct value to the search or commerce experience.
• General Guidelines on Random-Query Evaluation (PDF) - shows how sites can be classified based on their value, from vital to useful to relevant to not relevant to off topic to offensive

These raters may be used to

• help train the search algorithms, or
• flag low quality sites for internal reviews, or
• human review suspected spam sites

If Google bans or penalizes your site due to an automated filter and it is your first infraction usually the site may return to the index within about 60 days of you fixing the problem. If Google manually bans your site you have to clean up your site and plead your case to get reincluded. To do so their webmaster guidelines state that you have to click a request reinclusion link from within the Google Sitemaps program.

Google Sitemaps gives you a bit of useful information from Google about what keywords your site is ranking for and which keywords people are clicking on your listing.

Social Aspects

Google allows people to write notes about different websites they visit using Google Notebook. Google also allows you to mark and share your favorite feeds and posts. Google also lets you flavorize search boxes on your site to be biased towards the topics your website covers.

Google is not as entrenched in the social aspects of search as much as Yahoo! is, but Google seems to throw out many more small tests hoping that one will perhaps stick.They are trying to make software more collaborative and trying to get people to share things like spreadsheets and calendars, while also integrating chat into email. If they can create a framework where things mesh well they may be able to gain further marketshare by offering free productivity tools.

Google SEO Tools

• Google Sitemaps - helps you determine if Google is having problems indexing your site.
• AdWords Keyword Tool - shows keywords related to an entered keyword, web page, or web site
• AdWords Traffic Estimator - estimates the bid price required to rank #1 on 85% of Google AdWords ads near searches on Google, and how much traffic an AdWords ad would drive
• Google Suggest - auto completes search queries based on the most common searches starting with the characters or words you have entered
• Google Trends - shows multi-year search trends
• Google Sets - creates semantically related keyword sets based on keyword(s) you enter
• Google Zeitgeist - shows quickly rising and falling search queries
• Google related sites - shows sites that Google thinks are related to your site related:www.site.com
• Google related word search - shows terms semantically related to a keyword ~term -term

Business Perspectives

Google has the largest search distribution, the largest ad network, and by far the most efficient search ad auction. They have aggressively extended their brand and amazing search distribution network through partnerships with small web publishers, traditional media companies, portals like AOL, computer and other hardware manufacturers such as Dell, and popular web browsers such as Firefox and Opera.

I think Google’s biggest strength is also their biggest weakness. With some aspects of business they are exceptionally idealistic. While that may provide them an amazingly cheap marketing vehicle for spreading their messages and core beliefs it could also be part of what unravels Google.

As they throw out bits of their relevancy in an attempt to keep their algorithm hard to manipulate they create holes where competing search businesses can become more efficient.

In the real world there are celebrity endorsements. Google’s idealism associated with their hatred toward bought links and other things which act similarly to online celebrity endorsements may leave holes in their algorithms, business model, and business philosophy that allows a competitor to sneak in and grab a large segment of the market by factoring the celebrity endorsement factor into being part of the way that businesses are marketed.

Search Marketing Perspective

If you are new to a market and are trying to compete for generic competitive terms it can take a year or more to rank well in Google. Buying older established sites with aged trusted quality citations might also be a good way to enter competitive marketplaces.

If you have better products than the competition, are a strong viral marketer, or can afford to combine your SEO efforts with traditional marketing it is much easier to get natural citations than if you try to force your way into the index.

Creating a small site with high quality unique content and focusing on getting a few exceptionally high quality links can help a new site rank quickly. In the past I believed that a link was a link and that there was just about no such thing as a bad link, but Google has changed that significantly over the last few years. With Google sometimes less is more.

At this point sometimes buying links that may seem relatively expensive at first glance when compared to cheaper alternatives (like paying $299 a year for a Yahoo! Directory listing) can be a great buy because owners of the most spammy sites would not want to have their sites manually reviewed by any of the major search companies, so likely Yahoo! and Google both are likely to place more than average weight on a Yahoo! Directory listing.

Also getting a few citations from high quality relevant related resources can go a long way to improving your overall Google search relevancy.

Right now I think Google is doing a junky job with some of their search relevancy, by placing too much trust on older domains and favoring pages that have only one or few occurrences of certain modifiers on their pages. In doing this they are ranking many cloaked pages for terms other than the terms they are targeting, and I have seen many instances of things like Google ranking real content home mortgage pages for student loan searches, largely because student loans was in the global site navigation on the home mortgage page.

Learn More

• Google on SEO
• Google’s Webmaster Guidelines
• Google Spam Recognition Guide for Raters (doc)
• General Guidelines on Random-Query Evaluation (PDF)
• Google Blog
• Google AdWords
• Google AdWords Blog
• Google AdSense
• Google AdSense Blog
• Google Sitemaps
• Google Sitemaps Blog
• Papers Written by Googlers
• patent about information retrieval based on historical data

The search battle is general a battle for near perfect market data which can be leveraged in a near infinite number of ways, with each additional vertical or efficiency lending the network to a potentially larger scale AND an even greater network efficiency.Due to brand limitations and limited market size many vertical search services will remain unscathed by global search powerhouses, but as search improves in efficiency the major search engines will swallow many additional markets and make them more efficient.

OK, I take my vote…..

I vote for Google, even ask is really have an potential aspects to be more Google still had my attention for walking cause it’s so familiar, so How about you ?