The various types of CS:GO bans

There are 5 different type of bans in Counter-Strike Global Offensive. Here they are listed by their common name.
I) VAC bans: These are handed out for cheating and are permanent. For more information regarding VAC-bans go here.

II) Overwatch bans:
1.Minorly disruptive (griefing): Around 30 days/1 month.
2. Majorly disruptive (cheating -aim/wall/other external hacks): Permanent.
For more information regarding Overwatch-bans go here.

III) Account untrusted bans - These bans are permanent, 100% correct and won't be lifted. They will change into VAC ban over time.

IV) Competitive matchmaking bans
Competitive matchmaking cooldowns are handed out for leaving matches and not reconnecting in time (within 3 minutes).
Originally posted by Steam Support:
Player abandons, AFKing, excessive kicking and suiciding and teamkilling result in an undesirable experience for all of the other players in the game.

Our system is designed to limit the negative impact of users who repeatedly abuse these systems. If you perform these actions, Classic Competitive will be unavailable for a period of time.
For more information regarding matchmaking cooldowns go here.

V) Skill placement competitive cooldowns
As a new player, with less than 10 competitive wins, you will be limited to a certain amount of competitive games per day. See here.