Telegram Messenger, commonly known as Telegram, is an encrypted, cloud-based, cross-platform 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, live location, 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 provides end-to-end encryption in voice and video calls, and in optional private chats, which Telegram calls Secret Chats.

Telegram also has social networking features, allowing users to post stories, create large public groups with up to 200,000 members, or share one-way updates to unlimited audiences in so-called channels.The service also provides an open API for the creation of custom bots which can perform various tasks, integrate other services into Telegram chats, or work as mini apps.

Telegram was founded in 2013 by Nikolai and Pavel Durov. Its servers are distributed worldwide, while the headquarters are in Dubai, United Arab Emirates. Telegram is the most popular instant messaging application in parts of Europe, Asia, and Africa.

As of August 2023, Telegram has more than 800 million monthly active users, with India leading in the number of users. It was the most downloaded app worldwide in January 2021 with 1 billion downloads globally as of late August 2021.