A program that enables users to locate other ICQ users on the Internet and communicate with them in real time. ICQ, which homophonically stands for “I seek you,” lets you search for users currently online on ICQ networks and alerts you when friends go online. You can use ICQ to send real-time messages to other users, have group chat sessions, send e-mail, transfer files and URLs, play games, and so on. ICQ can even function as a universal platform for launching any peer-to-peer application, such as Microsoft NetMeeting.
When you install ICQ and begin the registration process, you are connected to an ICQ server that belongs to a network of such servers distributed across the Internet. During registration, you are given a unique number called an ICQ#, which identifies you to all other users on the ICQ network. You use your ICQ# to register your presence with the ICQ network when you go online and start ICQ, and to allow other ICQ users to recognize when you are online so that they can contact you. You can specify a list of ICQ friends, and an ICQ server will alert you when any of these friends go online.