Instant Messaging(IM) is a protocol for real-time communication over the Internet between communication partners. Instant messaging was standardized by the Internet Engineering Task Force( IETF) and uses the Transmission Control Protocol( TCP) or the Session Initiation Protocol( SIP).
Instant messaging is available for stationary desktop systems and as mobile instant messaging( MIM) for smartphones and tablets. Mobile instant messaging can be transmitted using all common carrier protocols. Packet-switched transport protocols offer good conditions for instant messaging, since work can be done in always-on mode and the messages appear directly on the display.
One of the first instant messaging services was "I Seek You"( ICQ). Instant messaging can be used to exchange e-mails and messages, as well as pictures, audio and video files. Messages are exchanged in real time or near real time, shortening communication processes. The Extensible Messaging and Presence Protocol(XMPP), formerly Jabber, provides for the exchange of files, voice, images and video. There are various IM clients. One of them is MSN Messenger from Microsoft, which was renamed Windows Live Messenger( WLM) and later integrated into Twitter.
Instant messaging services support and manage contact lists, the buddy lists, and allow users to customize their instant messages by inserting background images or privacy options to protect personal data.
Since instant messaging is a service offered by providers, there are now various free apps for smartphones with which messages and images can be exchanged in real time. The best-known app is WhatsApp, but there are also various messenger apps such as Telegram, Discord, Threema, Signal, Viber, Wire and others. Another messenger service with self-destructing images, is Snapchat.