There are 2 types of bans, a server ban and a platform ban.
A user with permissions to ban another user can ban a user either by going to their account menu and pressing Ban or click or by typing in a command to make a bot ban a user from the server. Users can also ban users that aren't in the server by typing in a ban command with their user ID and a bot would ban them. The ban will be permanent until a moderator unbans the user, bots can however be used to temporarily ban a user.
There are 2 different types of bans:
- Kick The user's account is removed from the server but they can join again if they want to.
- Ban The user's account is removed from the server and their account, their IP address and phone number are banned from joining the server, to prevent ban evasion, any accounts that are using the banned user's IP address and phone number won't be able to join the server. If the person comes back with a different account and uses a VPN (or a different IP address), that is a violation of the ToS and if they are reported, their account will be deleted.
If a user violates the Discord Terms of Service or the community guidelines, Discord's Trust and Safety Team can ban users.
- Warning: The user receives a DM and an email from Discord Trust and Safety warning them about the violation they committed.
- API Ban: The user is partially banned from accessing Discord's API usually for exceeding their rate limits frequently, e.g. spamming reactions. These bans usually last an hour, but sometimes can last longer.
- Temporary Ban: The user is temporarily banned from accessing Discord.
- Account Termination: The user's account gets disabled and then deleted later. They are allowed to make a new account. 
- Permanent Ban: The user is permanently banned from Discord. If the user had a phone number added to their account, their phone number is blacklisted from being used on any other account and a phone verification will be set on the user's IP address. They are not allowed to use Discord again.