Twitter is a microblogging site, one where users send out messages of no more than 140 characters. The messages, known as tweets, can be seen by anyone who follows the account. Twitter is free, but free as in kittens, not as in pizza. To use it effectively, it will take time to learn the language and develop content. When used effectively, Twitter offers libraries the chance to demonstrate to patrons how collections and services fit into their lives, while at the same time providing important information about user needs and opinions about the library. A well-developed Twitter network may also encourage communication with local organizations. All of this has the potential to help demonstrate the value of the libraries to patrons, and even introduce the library to a new audience. Twitter is all about sharing information, from breaking global news to personal photos. If their patrons are already sharing information in this way, it's time for libraries to join the conversation. (Contains 4 figures.)