Anti-cheat
Also said as Cheat detection, Kernel anti-cheat, VAC, Bans, Ban wave
Everything done to find and stop cheaters: software that looks for cheats on your machine, statistics on the server, and other players reviewing suspicious matches.
One cheater spoils the game for everyone else in the match. Every method has a cost, though, and the worst is banning an honest player, so most games wait for strong evidence and then ban in waves.
Say it
“Server-side stats first: flag anyone over three standard deviations on headshot rate across 1,000 shots, and send them to human review. Ban in weekly waves, so that cheat makers cannot tell which build was caught.”
Where you’ve seen it
Valve Anti-Cheat first shipped with Counter-Strike in 2002, and Valve presented VACNet, its machine-learning detector, at GDC in 2018. In 2023 a graphics driver update from AMD got honest Counter-Strike 2 players banned, and Valve pledged to reverse the bans.
Not to be confused with server authoritative
Authority removes whole kinds of cheating, because the server does not believe clients. Anti-cheat catches what is left, such as aim help, which looks exactly like a real player's inputs.