When a body gives off a scent others may find unpleasant, it is known as body odor. Body odor usually becomes evident if measures are not taken when a human reaches puberty. People who are obese, those who regularly eat spicy foods, as well as individuals with certain medical conditions, such as diabetes, are more susceptible to having body odor.

People who sweat too much, such as those with hyperhidrosis, may also be susceptible to body odor. However, often the salt level of their sweat is too high for the bacteria to break down. It depends on where the excess sweating is occurring and which type of sweat glands are involved.

Sweat itself is virtually odorless to humans. It is the rapid multiplication of bacteria in the presence of sweat and their breaking down of sweat into acids that eventually causes the unpleasant smell.

Body odor can have a pleasant and specific smell to the individual and can be used to identify people, especially by dogs and other animals. Each person's unique body odor can be influenced by diet, gender, health, and medication