Yahoo!
Crawling
Yahoo! does humble crawling for sites deeply so long as they have sufficient link popularity to get all their pages indexed. Yahoo!
may not want to deeply index sites with many variables in the URL string. You can use Yahoo! Site Explorer to see how well they are
indexing your site and how many sites link to your site.
Query accessing
If you search Yahoo! for something like "how to Get " many of the top ranked results will have "how to" and "Get" in the page
titles, which indicates that Yahoo! puts quite a bit of weight even on common words that occur in the search query. Yahoo! follows
text matching as compared to Google, which is more about concept matching.
Page vs Site
A few years ago, according to Search Engine Strategies conference, Yahoo! looked both at 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.
This is reasonable for new sites to rank in Yahoo! in as little as 2 or 3 months.
Editorial
Yahoo! has many editorial elements to their search product. If someone pays for Yahoo! Search Submit that content is reviewed
to ensure it matches Yahoo!'s quality guidelines, it automatically submits to the Yahoo! Directory .
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. Yahoo! also manually reviews some of the spammy categories
somewhat frequently and then reviews other samples of their index.
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.
Social Aspects
The picture of Yahoo's social aspects is well in clear when it is seen that it has paid millions of dollars to buy Del.icio.us
which is a social bookmarking site.
Yahoo also has 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.
Google
Crawling
Google has a new algorithm to help set crawl priority, crawl depth, and whether or not a site even gets crawled at all.
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.
Query Accessing
While I mentioned above that Yahoo! is common 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. Google and some of the other major search engines may try to answer many common related questions to the
concept being searched for. Some of the top results may answer specific relevant queries or be hard to beat, while others might be easy to compete with.
Page vs Site
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 that many people call the Google Sandbox. This can help you for a little time.
Site Age
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.
Editorial
Google is known to be far more aggressive with their filters and algorithms than the other search engines are.
In 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.
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 and blogs .
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.