Enable Developer Mode in Discord settings
Right-click the user, server, channel, message, or role
Select Copy ID
Paste the copied value where needed
On mobile, tap and hold the item
Tap Copy ID if Developer Mode is enabled
For your own user ID, right-click your profile in the desktop app or use a message you sent and copy the author ID
For a server ID, right-click the server icon and select Copy ID
For a channel ID, right-click the channel name and select Copy ID
For a message ID, right-click the message and select Copy ID