Discord bot
A program that logs in as its own member of a Discord server. It's registered in the developer portal and invited with a URL specifying its permissions — the same model as an OAuth app.
Technically there are two channels: a WebSocket connection receiving events in real time and a REST API for sending things back. Since 2021 interaction happens primarily through slash commands registered with Discord and surfaced in the client's interface, rather than the bot reading all text looking for a prefix. The latter now requires message content, a privileged intent that must be approved for larger bots — a 2022 change that shut down a great many hobby projects. Libraries: discord.py, discord.js, JDA. A bot must be verified to exist on more than a hundred servers.