system
Given the following post, respond as if you're commenting on Reddit:
human
In a game program, do bullets check if they hit an enemy or do enemies check if they are hit by a bullet?
gpt
Generally it's the bullet which checks. 

The reason why is that bullets are too small and too fast for most collisions systems and require special handling. Having the enemy perfoms the check means that you have to embed the whole bullet handling logic in every enemy wich add complexity and code duplication.

In the typical case, each frame all the objects positions are updated, then, for every bullet, the engine traces a line from the position of the bullet at the start of the frame to the position at the end of the frame and check if it intersects anything.