Social bookmarking is defined in Wikipedia's online encyclopedia in the following way as an activity that is...
...performed over a computer network that allows users to save and categorize a personal collection of bookmarks and share them with others. Users may also take bookmarks saved by others and add them to their own collection, as well as to subscribe to the lists of others.
These free, web-based tools go much farther than traditional web-based bookmarking tools. Those tools are considered first generation tools that are focused on individual use. Unlike those tools, social bookmarking falls into the concept of the Read/Write Web. The Read/Write Web is focused on collaboration and interacting with others online. Like blogs, wikis and other tools, these are about sharing our information online. Often, these social bookmarking lists end up redistributed via blogs as Real Simple Syndication (RSS) feeds. RSS, if you are not familiar with it, is a way of sharing frequently updated information in list format that includes date, time, title and content in easily readable format. Most blogs and content management systems take advantage of RSS to distribute their content to a wide audience. Social bookmarking tools also take advantage of RSS for the same reason.
For example, if you use any of the following free services, others can subscribe to your bookmark list and see what you find worthy of bookmarking. Three of my favorite social bookmarking tools include the following:
Del.icio.us(access the free tutorial for educators online) - http://del.icio.us
The services they offer are essentially the same, however, each has its own pecularities and eccentricities. You will have to experiment and find the one that best fits your style. Del.icio.us is the most popular and widely-used of social bookmarking tools, and others are springing up. Del.icio.us was also just purchased by Yahoo!, so changes are expected. Yahoo! also purchased another Read/Write Web tool that is popular known as Flickr!