Twitter is a project mainly written in PHP, it's free.
DO NOT USE THIS CLASS, use: http://github.com/tijsverkoyen/TwitterOAuth
!!! DONT USE THIS CLASS, it is deprecated. Use: https://github.com/tijsverkoyen/TwitterOAuth
Twitter is a service for friends, family, and co-workers to communicate and stay connected through the exchange of quick, frequent answers to one simple question: What are you doing?.
PHP Twitter is a (wrapper)class to communicate with Twitter.
PHP Twitter is BSD licensed.
The class is well documented inline. If you use a decent IDE you'll see that each method is documented with PHPDoc. More documentation can be found on http://classes.verkoyen.eu/twitter/docs.