Basically links are listed on a network, then whoever has access to that network can search for links that pertain to the keywords that person is searching for. Each link has three keywords associated with it, generally keywords that are optimized on their webpages, and when those keywords are searched for, ideally, it is that particular link that comes up.
The concept of social bookmarking can be compared to personal bookmarks, or favorites lists. These networks allow people to add links they like, not just their own. Social bookmarking can be used by anyone, but is generally utilized for business to business information, or business to consumer information.
When a link is ready to be put into a social bookmarking network, it is first tagged or submitted to a social bookmarking site. It is tagged with three keywords that are optimized on the website, and then a description of the website is added. From that point on, it can be searched through the keywords on the network.