Grand Theft Auto V (GTA V) has no built-in anti-cheat system. To stop cheating, it uses server-side checks and other safeguards. For instance, the servers for GTA V are made to ensure that users aren't using any illegal programs or hackers and to stop them from abusing bugs or flaws to their advantage. Aimbots and speed hacks are two examples of cheating that can be detected and prevented by the servers. It's important to remember that GTA V is an open-world game and does not have the same level of anti-cheat measures as more intense online multiplayer games. There are third-party programs out there that claim to be able to get around GTA V's cheat detection features, thus, some players may still be able to employ cheats or hacks to obtain an unfair edge in the game. Overall, GTA V is not as well protected against cheating as some other online multiplayer games, even though it has certain safeguards to stop it. If cheating in GTA V worries you, you might wish to play on servers or in lobbies that are more closely controlled, or you might want to employ third-party tools to help catch and prevent cheating.