Your site's ranking in Google search results is partly based on analysis of those sites that link to you. The quantity, quality, and relevance of links influences your ranking. The sites that link to you can provide context about the subject matter of your site, and can indicate its quality and popularity.
Any links intended to manipulate a site's ranking in Google search results may be considered part of a link scheme. This includes any behaviour that manipulates links to your site, or outgoing links from your site. Manipulating these links may affect the quality of our search results, and as such is a violation of Google’s Webmaster Guidelines.
The following are examples of link schemes which can negatively impact a site's ranking in search results:
• Buying or selling links that pass PageRank. This includes exchanging money for links, or posts that contain links; exchanging goods or services for links; or sending someone a “free” product in exchange for them writing about it and including a link
• Excessive link exchanging ("Link to me and I'll link to you")
• Linking to web spammers or unrelated sites with the intent to manipulate PageRank
• Building partner pages exclusively for the sake of cross-linking
• Using automated programs or services to create links to your site
The best way to get other sites to create relevant links to yours is to create unique, relevant content that can quickly gain popularity in the Internet community. The more useful content you have, the greater the chances someone else will find that content valuable to their readers and link to it. Before making any single decision, you should ask yourself: Is this going to be beneficial for my page's visitors?
It is not only the number of links you have pointing to your site that matters, but also the quality and relevance of those links. Creating good content pays off: Links are usually editorial votes given by choice, and the buzzing blogger community can be an excellent place to generate interest.