Links 101
What is a Link?
To answer what a Link is, we have to look at what a link really represents. In the early days of the web, links were a way to get from point A to B. It is a reference from one document to another and an integral means by which search engines index and find sites. In the early days of the web and search engines, if you were not linked to, you were not even found.
Depending on who links to you and how, determines your relationships to other documents (sites), keywords and subjects and your relevance. In essence, a link is a VOTE to a search engine, and the more votes, and the more high quality votes you have on a keyword, the more relevant you become, and hence more likely to rank highly for a related search result.
which leads to the next question…
Why Link?
Links are integral to sites which want to do well in Google or Yahoo’s Search Results Pages. The more links you have the more of a resource you become on keywords found on your site and in links pointing to you.
The more relevance you have as such, then the higher you should rank in Search Results Pages.