Instant messaging (IM) is a general term encompassing a variety of software applications that enable users to have real-time text conversations, play turn-based games, and share pictures, music, and data files over the Internet. IM software allows users to maintain a list of contactsgmdash;sometimes referred to as a buddy list—with whom they can exchange messages whenever both parties are online. These messages appear in a small window on the computer screen that both the sender and the recipient can see. The most popular IM utilities—such as America Online Instant Messenger (AIM), Microsoft MSN Messenger, and Yahoo! Messenger—also offer a number of other features, including chat rooms for groups to exchange messages and the capability to use voice communication and view streaming content over the Internet.

While each different IM utility is proprietary, they all work on a client-server model. Client software resides...