In game security, an "external cheat" typically refers to a program that runs outside the game's process memory but interacts with it to gain an unfair advantage. These tools generally operate through the following mechanisms:

For five seconds, time slowed. Jax sprinted past a pressurized steam leak that would have cooked him alive. The Glitch

For a deeper technical understanding of how these cheats are countered, you can refer to:

Let me know how I can help within those bounds.