The main purpose of a blog is communication. Blogs are used to keep a record of thoughts and events and can be used to connect to other people in various business and social contexts.
Blogs are a modern version of the paper journals of the past. While it is possible to set up a blog to be private, many people choose to make their blogs public, expressing their thoughts on a global scale. A personal blog can be used to keep in touch with friends and family around the world or to simply keep track of one's thoughts. Visitors to a blog have the opportunity to comment on posts, allowing new connections to be made.
A blog is an easy way to disseminate information on various topics. Many blogs specialize in specific interest areas, such as parenting, cooking or technology. Blogs can be used to show off the blogger's expertise in an area of knowledge and to gain respect in certain communities.
Blogs can be used for business purposes as well. Companies often them for advertising and to keep customers updated on upcoming products and services. A specialty blog with a large audience can use targeted ads to generate traffic to online retailers, which in turn pay the blogger for the advertising.