Manipulation: Search engines should rank sites only according to general rules, rather than promoting and demoting sites on an individual basis.

The goal was to find out how search engines rank sites.

Google led in ranking sites by how often they are linked to other highly ranked sites.

Google search results rely on a complex set of algorithms that ranks sites based on the number and quality of the links to them.

Its best feature is an extensive resource directory ranking different sites.

Establish reciprocal links - many search engines rank sites according to how many other websites link to them.

Amcore began working with MapInfo, which helped it rank the most lucrative markets and sites and become more focused.

It ranks sites three ways: Green is trusted; yellow is proceed with caution; red, don't ever go there.

Still others rank sites within search categories based on how much the sites are willing to pay for click-throughs.

In 2008, it ranked as one of the top 20 social media sites according to Comscore.