Social bookmarking is a way for people to store, organize, search, and manage “bookmarks” of web pages. Users save links to web pages that they like or want to share, using a social bookmarking site to store these links. These bookmarks are usually public, and can be viewed by other members of the site where they are stored. Examples of social bookmarking sites include del.icio.us and digg.com .
Most social bookmark services are organized by users applying “tags” or keywords to content on a Web site. This means that other users can view bookmarks that are associated with a chosen tag, and see information about the number of users who have bookmarked them. In many cases, users can also comment or vote on bookmarked items.
Social bookmarking is also interchangeably sometimes referred to as folksonomy, collaborative tagging, social classification, social indexing, and social tagging. “Folksonomy” is a combination of the words folk and taxonomy, hence a folksonomy is a taxonomy generated by a person or group of people
organize your bookmarks on social bookmarking sites by category. More simple answer
