Inbound links that contain semantically related anchor text to the content they point to have a positive effect on rankings. The copy surrounding the link, if present, may also do the same. Some even posit that this copy is as important as the link anchor text itself. Links with such surrounding copy are widely believed to be valued more by search engines, because links without copy surrounding it are frequently purchased and/or less indicative of a vote.
Manipulating link anchor text and the surrounding copy, if done en masse, can be used to manipulate
search results by creating a phenomenon called “Google bombing” (http://en.wikipedia.org/ wiki/Google_bomb). One popular example of this is illustrated, at the time of writing, with a query to Yahoo!, Google, or MSN, with the keyword “miserable failure.” The top result is the White House’s official biographical page for President George W. Bush, which doesn’t contain either of the words “miserable” or “failure” in the copy, but is linked from many sites that contain the words “miserable failure.” This particular Google bomb, and a few related ones, are described at http://en.wikipedia.org/wiki/Miserable_failure.
The importance of anchor text in SEO
When considering inbound links and search engine optimization, the anchor text you use to link to your website is the most important factor
What is Anchor Text?
Anchor text is the clickable text that is associated with a link.
Using Long Link Text
Long links that explain what the referenced page is about are a great thing not only for visitors but also for search engines.