If you have played an online multiplayer game, it is most likely that you have also encountered a hacker. Hackers exist for the sole reason of ruining else’s gameplay so that they can cheat their way to the top.
Hackers are often found inside fps shooter games, where they can best utilise aimbots and wallhacks. Aimbots are programs that identify where the enemy players are, and automatically shoot directly at them. There are also wallhacks, which work by identifying all the player locations from the server information and highlighting them to the player so that the player can see and ambush enemies.
Aimbots can be hidden by using an FOV monitoring script, which stops the aimbot from swinging around suddenly and firing backwards, which is an obvious giveaway. But wallhacks are much easier to disguise, as they are a receiver-end cheat, rather than a server-end cheat. Sometimes you will be able to tell if someone is wallhacking because they are always able to ambush you, but this does not always mean that someone is cheating.
Cheaters are commonly found in popular games with a large player base. This is because in popular games, you will find more people who are frustrated over them and will be willing to buy hacks just so that they can spite the players who once ruled over them. People with this mindset are often the kind of players who everybody hates playing against, because as soon as they lose, they go ballistic before rage quitting.
Some games have anti-cheats, which can stop hackers in many ways, such as checking assets and executables to make sure that they have not been modified, statistical analysis, and sometimes even users can help by reporting hackers. It can be anything, but it depends on what the game is, and they need to be constantly updated to avoid hackers finding workarounds.
Overall, there are some people who will manage to stop certain hackers, but there will always be people who try and find ways to break and exploit things.