Body odour has a reputation problem. It is often treated as a hygiene failure or a social offence. In reality, it is biology at work, plus a big helping of culture.
Most body odour is not produced by sweat itself. Sweat is largely odourless. Smell develops when bacteria (and sometimes fungi) on the skin break down compounds in sweat and skin oils, producing pungent byproducts. That is why odour is often strongest in warm, moist areas with lots of sweat glands, such as armpits, feet and the groin. It is also why two people can smell very different after the same workout. Their skin chemistry and microbiomes differ.
