B2 was one of the first major blog authoring software packages offered on the web. In 2003, it was used as the blog platform on around 2000 blogs. It was written to take advantage of the easy availability of PHP and MySQL. B2 was developed by Michel Valdrighi, who went on to develop the popular blog software platform WordPress. B2 is no longer supported, but it is still available as an installation package on many web hosts and some bloggers still use the b2 platform.

To run b2, your server must be able to run PHP4. You should also have a MySQL database configured. There is support for extended blog entries, including multiple page blog posts. The final version of b2 include a blog search feature.

B2 supported pingbacks and Trackback. CCS support was added to later b2 releases, making it easier for bloggers to change the appearance of their blog. Users were accorded one of four different security levels, from level one when users were not allowed to post comments or entries, to level four, when users were granted full administrative powers.

B2 was supplanted by WordPress, which has gone on to become popular. B2evolution, while not the official successor to b2, has been based on the original b2 blog platform.