With both blogs and forums, you can post a comment and reply to other comments, thus developing discussions.
Microblogging is a broadcast medium that exists in the form of blogging.
Media sharing sites allow you to upload your photos, videos and audio to a website that can be accessed from anywhere in the world.
A social news website features user-posted stories that are ranked based on popularity, as voted on by other users of the site or by website administrators.
Social bookmarking is a centralized online service which allows users to add, annotate, edit, and share bookmarks of web documents.
A social network is a social structure made up of a set of social actors (such as individuals or organizations), sets of dyadic ties, and other social interaction between actors.