Even if the clothing in their armpit isn't soaking, the distinctive smell is obvious.
Body odour is embarrassing, it spoils clothes, and can ruin a person's social life.
Covering our body are around 3 million sweat glands. Most body odour comes from the armpits and groins, where the sweat is produced by glands called apocrine glands. The sweat produced in these hairy areas is milk-like and rich in protein. These glands respond to the hormone testosterone - which is why sweating and BO are more common after puberty. Sweat produced from the rest of the body is made by different glands - called eccrine glands.