Google tries to return the most relevant results for a given search query or key phrase. One way Google does so is by searching for and analyzing keywords on pages of other websites that link to your site. What other sites “say” about your site through their link text, the title of their Links page, and the content of their Links page can be almost as important as what your own web pages say! This means that the quality of links may be as important as the quantity of links to your site.
You could have hundreds of pages linking to your site, but if the text of those links doesn’t match your keywords, or if the linking page content is not related to your site, those links by themselves probably won’t add any appreciable boost to your ranking. If only the quantity of links to a site were important, every site on the Web would link indiscriminately with every other site and the site with the largest number of incoming links would be #1 for a given keyword. This clearly is not the case.
Specifically, the quality of a link on another site that points to your site is determined
by the following factors:
1. Text of the link – does it contain your keywords? (This very important)
2. Text of other links on the same page – do they also contain, or are similar to, your keywords?
3. Is the link contained in a paragraph on the page, surrounded by related text. Such “inline” links are weighted higher than links that are simply listed on a page without any other non-link text.
4. Title of the linking page – does it contain, or is it related to, your keywords?