Instant messaging (often shortened to IM) is a way of two or more people to communicate over a network. When the sender sends a message, this message is sent to all the recipients in the group. People use messaging clients to send and receive messages. The type of message supported depends on the specific client, and network. Most of the time, it is text. In some cases, images or other types of media is supported.
Instant messaging services got many ideas from an older and still popular way to online chat named Internet Relay Chat (IRC). In early instant messaging programs, each letter appeared when it was typed and when letters were deleted to correct typos. These were also seen by the reader. This made it more like a telephone conversation than sending letters. In newer instant messaging programs, the other readers in the conversation generally only sees each line of text right after a new line is started. Most instant messaging programs have a way to set a status message. This works likes the message on a telephone answering machine. It shows whether or not people are online and want to chat.
Benefits
Instant messaging offers real-time communication and allows easy collaboration, which might be considered more akin to genuine conversation than email's "letter" format. In contrast to e-mail, the parties know whether the peer is available. Most systems allow the user to set an online status or away message so peers are notified when the user is available, busy, or away from the computer. On the other hand, people are not forced to reply immediately to incoming messages. For this reason, some people consider communication via instant messaging to be less intrusive than communication via phone. However, not all popular systems allow the sending of messages to people not currently logged on (offline messages), thus removing much of the difference between IM and email.
Instant messaging allows instantaneous communication between a number of parties simultaneously, by transmitting information quickly and efficiently, featuring immediate receipt of acknowledgment or reply. In certain cases IM involves additional features, which make it even more popular, i.e. to see the other party, e.g. by using ((web-cams)), or to talk directly for free over the internet.
It is possible to save a conversation to read later or look at again. Instant messages typically are may be logged in a local message history which closes the gap to the persistent nature of e-mails and facilitates quick exchange of information like URLs or document snippets (which can be unwieldy when communicated via telephone).
People with an auditory or speech disability
Instant messaging opens new methods of spontaneous communication for people that have an impairment in hearing, auditory processing, or speech. It is considered by many a powerful way to allow equal opportunities in communication, without the aid of special devices or services designed for users with hearing loss.
Friend-to-friend networks
Instant Messaging may be done in a Friend-to-friend network, in which each node connects to the friends on the friendslist. This allows to communicate to friends of friends and build chatrooms for instant messages with all friends on that network.
Business application
Instant messaging has proven to be similar to personal computers, e-mail, and the WWW, in that its adoption for use as a business communications medium was driven primarily by individual employees using consumer software at work, rather than by formal mandate or provisioning by corporate information technology departments. Tens of millions of the consumer IM accounts in use are being used for business purposes by employees of companies and other organizations.
In response to the demand for business-grade IM and the need to ensure security and legal compliance, a new type of instant messaging, called "Enterprise Instant Messaging" ("EIM") was created when Lotus Software launched Lotus Sametime in 1999. Microsoft followed suit shortly thereafter with Microsoft Exchange Instant Messaging, and later created a new platform called Microsoft Office Live Communications Server. Since then, both IBM Lotus and Microsoft have introduced federation between their EIM systems and some of the public IM networks thus employees may use a single interface to both their internal EIM system and their buddies on AOL, MSN, and Yahoo!. Current leading EIM platforms include IBM Lotus Sametime, Microsoft Office Live Communications Server, and Jabber XCP .