Instant messaging (IM) allows for real-time communication through computers and mobile devices by exchanging private or group messages similar to email. The first IM program was developed in 1987, and major platforms like AOL and MSN launched in the late 1990s. IM is popular among teens and college students, and is used for both personal and institutional communication like online library reference desks. Key features include text, video and file sharing, as well as presence awareness of when contacts are online.