Trackback spam is when spammers use the Trackback protocol (originally created by SixApart) to post their links to blogs. It is a form of Blog spam, and is popular with spammers due to the simplicity of the trackback process.

Trackback spam generally relies on the automated nature of trackbacking to insert many links in a wide variety of posts. It only affects blogging tools that accept Trackback, such as TypePad, Wordpress, Blogger, and MovableType blogs.