VAC Ban:

A VAC ban is a Valve Anti-Cheat penalty that restricts a Steam account after cheat software or other prohibited game tampering is detected in Counter-Strike 2 or another VAC-protected game.

In Counter-Strike 2, a VAC ban matters because it marks an account as having violated anti-cheat rules, which can prevent fair play, damage trust in matchmaking, and affect access to secure online features tied to Steam. It is commonly discussed when a player is removed from a match, accused of cheating, or has a profile that shows a ban history. For example, if a player uses an external aim assist and Valve’s anti-cheat system later detects it, the account can receive a VAC ban and be flagged on the Steam profile.

Related: VAC (Valve Anti-Cheat), Matchmaking, Overwatch