What is MTProto?

MTProto is Telegram’s own protocol to communicate with their API when you connect to their servers.

Telethon is an alternative MTProto-based backend written entirely in Python and much easier to setup and use.

Both official applications and third-party clients (like your own applications) logged in as either user or bots can use MTProto to communicate directly with Telegram’s API (which is not the HTTP bot API).

When we talk about MTProto, we often mean “MTProto-based clients”.