Telegram is a cloud-based, cross-platform instant messaging service that allows users to exchange messages, share media and files, and hold private and group voice or video calls, as well 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, known as Secret Chats).

Telegram was founded in 2013 by Nikolai and Pavel Durov, and its servers are distributed worldwide, while the headquarters are in Dubai, United Arab Emirates). 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).

Telegram uses a custom build symmetric encryption scheme called MTProto, which is based on 256-bit symmetric AES encryption, 2048-bit RSA encryption, and Diffie–Hellman key exchange). Telegrams security model has received praise and notable criticism by cryptography experts).

Telegram is known for its speed, syncing capabilities, and ease of use. It also offers powerful photo and video editing tools, animated stickers and emoji, fully customizable themes to change the appearance of the app, and an open sticker/GIF platform to cater to all your expressive needs. For those interested in maximum privacy, Telegram offers Secret Chats, which can be programmed to self-destruct automatically from both participating devices.

Overall, Telegram is a popular messaging app that offers a range of features and security options. However, as with any app, users should be aware of potential privacy concerns and evaluate their own threat model before deciding to use it.