Why should you ask about the difference between search engine algorithms? As I have mentioned in previous posts, though Google is the big daddy of search, it is important to know the difference between the algorithms used by different search engines. The truth though is that when it comes to Google, Yahoo!, and MSN there isn’t much difference, at least in terms of the basic principle. Ask uses a different approach though.
If you look at the Ask Algorithm (read the short answer if you want a less amusing but easier to understand answer) you will see that Ask places emphasis not only in the number of inbound links but also previous user click streams to help determine a site’s actual popularity. This is a good thing in the sense that the search engine actually gets to determine (with each click) which sites are really relevant to the search terms since people will click on those sites more. However, aside from the click streams, Ask also differs in their approach with regards to links.
With Google, MSN and Yahoo! inbound links from ALL sites (which the search engines bots have taken note of) count. Of course, the quality of the sites containing the link helps determine the links’ quality but the point is that these links, regardless of whether the referring site is relevant to your website or not, help determine your link popularity. With Ask they are more strict about link popularity and only counts the links from sites with topics relevant to your site.
For SEOs what this means is that we need to employ a different kind of link building strategy with Ask in the sense that we should be focusing on relevant sites more. In the end, this will also benefit your SEO efforts in Google, MSN, and Yahoo! because they also place value in link relevance. However, this makes it harder for sites with broad topics and new sites, which haven’t built up a solid reputation (and thus lots of inbound links) in their niche.