Cheating

Counter-Strike has been a prime target for exploitation by cheaters since its release. In-game, cheating is often referred to as 'hacking' (though this is technically incorrect - it is the programmers, not the users, of the cheats that might be regarded as hackers).
Typical cheats are:
Wallhacks, which allow the player to see through walls. These work by altering the display driver to display objects that are normally obscured.
Speedhacks, which give the player increased speed. These work by sending false synchronisation data to servers.
No recoil, which keeps the players gun shooting straight without a kickback by removing gun physics.
Aimbots, which help the player aim at enemies. These work by moving the player's view to anticipate an enemy's position.
ESP, which shows textual information about the enemy, such as, health, name, and distance
Barrel hack, which shows a line that depicts where the enemy is looking
Anti-flash and anti-smoke, which remove the flashbang and smoke grenade effect.
Grenade Dodger, which moves player farther or closer to a grenade, depending on settings.
Valve has implemented an anti-cheat system called Valve Anti-Cheat (VAC). Players cheating on a VAC enabled server risk having their account permanently banned from all VAC secured servers.
With the first version of VAC, a ban took force almost instantly after being detected, and the cheater had to wait 2 years to have the account unbanned. Since VAC's second version, cheaters are not banned automatically. Rather, they are banned according to a delayed banning system, and bans are never lifted. Many cheats are still not detected by VAC, and often the only effective anti-cheat device is a human administrator watching an online game, however; it can be very difficult to differentiate between skill, luck and cheating and server admins only have the power to ban users from their server