Slack API
Tokens
The Slack API has various tokens that it uses for different functions.
That is, you can use the Slack API from multiple perspectives.
Either that of yourself, so something to automate your own user. It would be able to read/write messages and do pretty much anything as you.
Or as a bot user, like a different unique user on the server. It can only send messages it is in the channels of, etc.
Both tokens and the permissions that they grant are on the OAuths and Permissions page of any Slack app.
The user and bot scopes are under different headings.