With a lot of modern bombs, there is generally some form of guidance system to puts the warhead on target.
With older stuff, there may be a sighting system of some sort, but that would probably be about it. The bombs will fall in roughly the right area. There is a bit of a caveat to this, which is dive bombers. They would put the plane into a very steep dive before releasing the bomb, theoretically giving a better chance of hitting something.
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