VAC stands for Valve Anti-Cheat, Valve’s cheat detection software. Players who are caught using cheats on a VAC-secured server will be issued a VAC ban, banning them from VAC-secured servers for that particular game in the future and putting a mark on their Steam profile that can’t be hidden from public view. VAC bans are permanent, non-negotiable, and cannot be removed by Steam Support. Players who have gotten a VAC ban are sometimes referred to as going on a ‘permanent VACation’.