In humans, sweating and body odor often go hand in hand, although for the most part, human sweat has little or no odor on its own. The odor associated with sweat is actually caused by bacteria that naturally lives on the skin. Though most sweat is relatively odorless, sweat released under high stress can have a strong unpleasant odor of its own. Both sweating and body odor can be controlled through the use of a number of products, especially antiperspirants and deodorants.
There are two types of sweat that humans produce. The first kind of sweat it called eccrine sweat and is produced all over a person's body. This kind of sweat is made up primarily of water and salt though there are small amounts of other chemicals in it as well. Eccrine sweat occurs when a person becomes overheated when the temperature is hot or a person is exercising. This type of sweating and body odor are not immediately connected because this sweat is not particularly odorous on its own.
Though eccrine sweat does not have very much smell, it can start to smell after a while. When the body is wet, bacteria is able to quickly reproduce on the surface of the skin. This bacteria can cause an offensive odor, often after only an hour or so. The smell from this bacteria gets worse until the sweat is washed off of the body and clothing.
In order to control eccrine sweating and body odor, the best thing to do is to shower frequently. Washing the skin will help lower the number of bacteria on it even though it won't eliminate the bacteria completely. Eccrine sweat can also produce an unpleasant odor if a person's diet is composed of foods with strong odors, such as garlic and spices.
The other type of sweat that a person produces occurs around the hair follicles after a person has been through puberty. This type of sweat is called apocrine sweat and is associated with a strong odor. It is made up of fat as well as water and salt and remains in the hair follicles until it is pressed out when a person undergoes stress. The connection between apocrine sweat and body odor is immediately apparent because it doesn't need to wait for bacteria to multiply in order to smell but has a strong odor on its own. This type of sweat is usually controlled through the use of underarm antiperspirants and deodorants.