Blogs, short for web logs, are like online journals for a particular person. The owner will post a message periodically, allowing others to comment. Topics often include the owner's daily life, views on politics or a particular subject important to them.

Blogs mean many things to different people, ranging from "online journal" to "easily updated personal website." While these definitions are technically correct, they fail to capture the power of blogs as social software. Beyond being a simple homepage or an online diary, some blogs allow comments on the entries, thereby creating a discussion forum. They also have blogrolls (i.e. links to other blogs which the owner reads or admires) and indicate their social relationship to those other bloggers using the XFN social relationship standard. Pingback and trackback allow one blog to notify another blog, creating an inter-blog conversation. Blogs engage readers and can build a virtual community around a particular person or interest. Examples include Slashdot, LiveJournal, BlogSpot. Blogging has also become fashionable in business settings by companies who use software such as IBM Lotus Connections.