Telegram Messenger, commonly known as Telegram, is a cloud-based, cross-platform, encrypted instant messaging (IM) service. It was originally launched for iOS on 14 August 2013 and Android in October 2013. It allows users to exchange messages, share media and files, and hold private and group voice or video calls as well as public livestreams. It is available for Android, iOS, Windows, macOS, Linux, and web browsers. Telegram also offers end-to-end encryption in voice and video calls, and in optional private chats, which Telegram calls Secret Chats.

Instant messaging (IM) technology is a type of online chat allowing immediate transmission of messages over the Internet or another computer network. Messages are typically transmitted between two or more parties, when each user inputs text and triggers a transmission to the recipient(s), who are all connected on a common network. It differs from email in that conversations over instant messaging happen in real-time. Most modern IM applications use push technology and also add other features such as emojis, file transfer, chatbots, voice over IP, or video chat capabilities.