Instant messaging or IM is a form of real-time communication between two or more people based on typed text. The text is conveyed via computers connected over a network such as the Internet.
Instant messaging requires the use of a client program that hooks up an instant messaging service and differs from e-mail in that conversations are then able to happen in realtime. Most services offer a presence information feature, indicating whether people on one's list of contacts are currently online and available to chat. This may be called a contact list. In early instant messaging programs, each letter appeared as it was typed, and when letters were deleted to correct typos this was also seen in real time. This made it more like a telephone conversation than exchanging letters. In modern instant messaging programs, the other party in the conversation generally only sees each line of text right after a new line is started. Most instant messaging applications also include the ability to set a status message, roughly analogous to the message on a telephone answering machine.
Popular instant messaging services on the public Internet include .NET Messenger Service, AOL Instant Messenger, Excite/Pal, Gadu-Gadu, Google Talk, iChat, ICQ, Jabber, Qnext, QQ, Skype and Yahoo! Messenger. These services owe many ideas to an older (and still popular) online chat medium known as Internet Relay Chat (IRC).
Instant messaging typically boosts communication and allows easy collaboration. In contrast to e-mails, the parties know whether the peer is available. Most systems allow the user to set an online status or away message so peers get notified whenever the user is available, busy, or away from the computer. On the other hand, people are not forced to reply immediately to incoming messages. This way, communication via instant messaging can be less intrusive than communication via phone, which is partly a reason why instant messaging is becoming more and more important in corporate environments. Also, the fact that instant messages typically get logged in a local message history closes the gap to the persistent nature of e-mails, facilitating quick, safe, and persistent exchange of information such as URLs or document snippets, which can be unwieldy when done using inappropriate media such as phone.
An early and partial form of messaging systems was implemented on private computer networks such as the PLATO system in the early 1970s. It was also available in the 1970s on the DEC PDP-11 as the "talk" program. Later the Unix/Linux "talk" messaging systems were widely used by engineers and academics in the 1980s and 1990s to communicate across the internet. MIT's Project Athena created the first instant messaging tool in 1987 with the graphical Zephyr client. PLATO was the first instant messenger combining presence or list of contacts with the ability to send messages. AOL had 6M subscribers using instant messaging when an Israeli company named Mirabilis introduced ICQ in November 1996 and was first to introduce this concept freely on the Internet. When the number of users of ICQ became a threat to AOL instant messaging service, AOL acquired Mirabilis/ICQ. A few years later AOL/ICQ was awarded two patents from the U.S. patent office. After its introduction, a number of variations of instant messaging have arisen in parallel in many places such as (Yahoo, MSN, Excite, Ubique), each with its own protocol. More secure corporate and commercial oriented solutions for instant messaging were introduced by IBM/(Lotus Sametime) and by others. This has led to users running many instant messaging applications simultaneously to be available on several networks. Multiprotocol clients such as Gaim, Trillian and Miranda reduce the need for independent clients for each protocol.
On single line bulletin board systems (BBS), the system operator (sysop) and the single caller online could typically chat with one another. One's typing appeared in real time for the other person as an instant message equivalent.
Recently, many instant messaging services have begun to offer video conferencing features, Voice Over IP (VoIP) and web conferencing services. Web conferencing services integrate both video conferencing and instant messaging capabilities. Some newer instant messaging companies are offering desktop sharing, IP radio, and IPTV to the voice and video features.
On December 19, 2002, AOL Time Warner announced that ICQ had been issued a United States patent for instant messaging, but they also said that they had no plans on enforcing their patent at the present time.
The term "instant messenger" is a service mark of Time Warner and may not be used in software not affiliated with AOL in the United States. For this reason, the instant messaging client formerly known as GAIM or gAIM is now only to be referred to as Gaim or gaim.
What really characterizes instant messaging from other forms of text messaging applications is the use of "presence" which enables the user of an instant messaging applications to rendez-vous with his/her counterparties and see their status of availability.
There have been several attempts to create a unified standard for instant messaging: IETF's SIP (Session Initiation Protocol) and SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions), APEX (Application Exchange), Prim (Presence and Instant Messaging Protocol), the open XML-based XMPP (Extensible Messaging and Presence Protocol), more commonly known as Jabber and OMA's (Open Mobile Alliance) IMPS (Instant Messaging and Presence Service) created specifically for mobile devices.
Most attempts at creating a unified standard for the major IM providers (AOL, Yahoo! and Microsoft) have failed and each continues to use its own proprietary protocol.
However, while discussions at IETF were stalled, Reuters head of collaboration services, David Gurle (the founder of Microsoft's Real Time Communication and Collaboration business), surprised everybody by signing the first inter-service provider connectivity agreement on September 2003. This historic agreement enabled AIM, ICQ and MSN Messenger users to talk with Reuters Messaging counterparts and vice-versa against an access fee. Following this breakthrough agreement between networks Microsoft, Yahoo! and AOL came to a deal where Microsoft's Live Communication Server 2005 (which is interestingly also used by Reuters for its Reuters Messaging service) users would also have the possibility to talk to public instant messaging users. This deal settled once for all the protocol for interconnectivity in the market as SIP/SIMPLE and established a connectivity fee for accessing public instant messaging clouds. Separately, on October 13, 2005 Microsoft and Yahoo! announced that by (the Northern Hemisphere) summer of 2006 they would interoperate using SIP/SIMPLE which is followed on December 2005 by the AOL and Google strategic partnership deal where Google Talk users would be to talk with AIM and ICQ users provided they have an identity at AOL.
There are two ways to combine the many disparate protocols:
- One way is to combine the many disparate protocols inside the IM client application. Examples include iChat, Trillian, Gaim, Fire, Proteus, Miranda IM, Adium, Everybuddy, Ayttm, Kopete, Centericq, BitlBee, Windows Messenger, and IMVITE.
- The other way is to combine the many disparate protocols inside the IM server application. This approach moves the task of communicating to the other services to the server. Clients need not know or care about other IM protocols. For example, LCS 2005 Public IM Connectivity. This approach is popular in Jabber/XMPP servers however the so-called transport projects suffer the same reverse engineering difficulties as any other project involved with closed protocols or formats.
Some approaches, such as that adopted by the Sonork enterprise IM software or the Jabber/XMPP network or Winpopup LAN Messenger or Softros LAN Messenger, allow organizations to create their own private instant messaging network by enabling them to limit access to the server (often with the IM network entirely behind their firewall) and administer user permissions. Other corporate messaging systems, like the Medianet Innovations MIC, allow registered users to also connect from outside the corporation LAN, by using a secure firewall-friendly HTTPS based protocol. Typically, a dedicated corporate IM server has several advantages such as pre-populated contact lists, integrated authentication, and better security and privacy.
Some networks have made changes to prevent them from being utilized by such multi-network IM clients. For example, Trillian had to release several revisions and patches to allow its users to access the MSN, AOL, and Yahoo! networks, after changes were made to these networks. The major IM providers typically cite the need for formal agreements as well as security concerns as reasons for making these changes.
- AIM: 53 million active users (Nielsen//NetRatings, August 2005), 195 million total (January 2003).
- Windows Live Messenger: 29 million active (Nielsen//NetRatings, August 2005), 155 million total (April 2005).
- Yahoo! Messenger: 21 million active (September 2005).
- ICQ: 20 million active world wide, 400 million total.
- QQ: 20 million peak online users, 221 million active users
- Skype: 7 million peak online users (August 2006), 100 million total (April 2006).
- Jabber: 13.5 million enterprise users (Osterman Research August 2005), this does not count users via ISPs and other service providers (estimated to be more than 7.5 million, for a total of at least 21 million).
- Sametime: 15 million enterprise users.
- Gadu-Gadu: 5.6 million total (June 2006).
- MXit: 2 million (majority in South Africa and more then 150,000 international) ([http://www.busrep.co.za/index.php?fSectionId=553&fArticleId=3493277 Business Report, 19 October 2006)