Exchanging text messages in real time between two or more people logged into a particular instant messaging (IM) service. Instant messaging is more interactive than e-mail because messages are sent immediately, whereas e-mail messages can be queued up in a mail server for seconds or minutes. However, there are no elaborate page layout options in instant messaging as there are with e-mail. The basic operation is simple: type a brief message and press Enter.|
Instant messaging services may also provide video calling, file sharing, PC-to-PC voice calling and PC-to-regular-phone calling. Instant messaging has promoted IP telephony because the IM software makes it easy to switch from "text chat" to "voice chat" if the user has a headset or microphone and speakers.
In order to set up an instant message, you have to add the usernames of the people you want to message with to your "buddy list" (friend list, contact list). When they log in to the Internet with their IM software, and provided they have not configured themselves as "invisible," you are instantly alerted. When they log out, you are also notified. Each system has its own method for blocking incoming and outgoing messages.
The IM Services
Instant messaging (IM) became popular after Israeli-based ICQ introduced its service in 1996, which was later acquired by AOL. The major IM services are AOL's Instant Messenger (AIM), ICQ, Yahoo! Messenger, Google Talk, Jabber and Microsoft's incarnations: MSN Messenger, Windows Messenger and Windows Live Messenger. See AIM, ICQ, Yahoo! Messenger, Google Talk, Jabber, MSN Messenger, Windows Messenger and Windows Live Messenger.
Although third-party IM clients such as Trillian (www.ceruleanstudios.com) and Simple Instant Messenger (http://sim-im.berlios.de) were designed to interface with multiple IM services, the IM clients from the IM service itself were always proprietary to that service. Google changed that practice by basing Google Talk on the open XMPP protocol used in Jabber, which is supported by the open source community (see XMPP). See IRC, chat, chat room, voice over IM and IMUnified.
This snippet from Google Talk shows a typical text interaction: short and not elaborate. The user's picture can be real or selected from a list of fantasy figures (see