How it works
Gateway intents decide which events Discord sends your bot. You pass them as one number when you connect. Asking for fewer intents means less traffic and fewer permissions to explain.
Tick the intents you need and copy the value. Three are privileged: Server Members, Presence, and Message Content. You have to switch those on in the Discord Developer Portal (Bot tab), and bots in 100 or more servers need Discord’s approval to use them.
Already have a number? Paste it to see which intents it includes.
Questions
Why is my bot not seeing message text?
Reading message content needs the privileged Message Content intent, both in your code and switched on in the Developer Portal.
What are privileged intents?
Server Members, Presence, and Message Content. They expose more user data, so Discord makes you enable them manually and verify larger bots.
Do slash commands need intents?
No. Slash command interactions arrive without any intents. Only gateway events like messages, members, and reactions need them.