system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does soap work?

How does it keep off bacteria/smells?
gpt
Some molecules dissolve in water, and some dissolve in oils or fats. So if you get grease or oil on you (like from your own skin),  water won't do much to get it off, because they won't mix. This grime can harbor bacteria that can make you stink and make you sick.

Soaps basically contain molecules with one end that dissolves in water and one end that dissolves in oils, so that when you lather it up on your skin, it can stick to the grime and at the same time stick to water, so the water can wash the grime away.