Cuil founder Tom Costello has published an interesting article (discussed at WebmasterWorld forums) sharing his findings on the differences between Google, Yahoo and Bing search engines.
While the whole article has plenty of smart observations and ideas and is definitely a recommended reading, what I found especially interesting were the differences in how Google and Bing use signals to evaluate the site relevance and quality.
A second major question is whether Bing is using any new signals, beyond what are usually used in search engines. Search engines use traditional signals like title, URL, emphasis/heading, document length and number of occurrences on page to generate an on-page score. They then make an off page score from a count of matching anchors, possibly weighted by the quality of the source page. They combine these scores with some proximity information, and some notion of page popularity (e.g. PageRank). Finally they demote spam and they promote pages that are clicked on for this query more than one would expect.
While Bing doesn’t seem to use any new signals to evaluate the site relevance, its algorithm does have some differences:
- Bing gives stronger emphasis to keywords in URLs;
- Bing seems to give more weight to capitalized terms;
- Bing prefers pages from large sites.
I summarized all findings in a small table (you knew I would!) for you to easier get the idea. However you should definitely check the article itself to look through actual examples and numbers:
|The ratio of spam||2,5%||4,9%||2,9 %|
|URL matching||moderate impact||moderate impact||high impact|
|Letter capitalization||moderate impact||moderate impact||high impact|
|Differences in SERPs|