Social bookmarking is a way for Internet users to store, organize, share and search bookmarks of web pages. In a social bookmarking system, users save links to web pages that they want to remember and/or share. These bookmarks are usually public, but depending on the service's features, may be saved privately, shared only with specific people or groups, shared only inside certain networks, or another combination of public and private. The allowed people can usually view these bookmarks chronologically, by category or tags, via a search engine, or even randomly.

Most social bookmark services encourage users to organize their bookmarks with informal tags instead of the traditional browser-based system of folders, although some services feature categories/folders or a combination of folders and tags. They also enable viewing bookmarks associated with a chosen tag, and include information about the number of users who have bookmarked them. Some social bookmarking services also draw inferences from the relationship of tags to create clusters of tags or bookmarks.

Many social bookmarking services provide web feeds for their lists of bookmarks, including lists organized by tags. This allows subscribers to become aware of new bookmarks as they are saved, shared, and tagged by other users.

As these services have matured and grown more popular, they have added extra features such as ratings and comments on bookmarks, the ability to import and export bookmarks from browsers, emailing of bookmarks, web annotation, and groups or other social network features.

Tags are one-word descriptors that you can assign to your bookmarks to help you organize and remember them. Tags are a little bit like keywords, but they're chosen by you, and they do not form a hierarchy. You can assign as many tags to a bookmark as you like and rename or delete the tags later. So, tagging can be a lot easier and more flexible than fitting your information into preconceived categories or folders.

For example, if you save an article about how to make a certain kind of cake, you can tag it with recipes sweets yogurt or whatever other tags you might use to find it again. You don't have to rely on the designer of a system to provide you with a category for French cake recipes. You make up tags as you need them, and use the tags that make the most sense to you.