You've got two types of sweat glands across your skin (a third type, the sebaceous gland is similar in structure and function, but produces sebum, not sweat). They serve as a part of the integumentary system, which is also composed of your hair, fingernails and skin. The sweat glands serve on another system as well, the excretory system. The first type of sweat gland that develops is the eccrine gland. It's found all over your skin, but most abundantly on the palms of your hands, the soles of your feet, your underarms (axillae) and your forehead.
Eccrine sweat glands are activated when the hypothalamus senses the body's internal temperature is rising. Sweat composed mainly of water and salts is released and the body cools down. Since eccrine gland sweat is mostly water and salt, it doesn't tend to produce a scent, so it's not responsible for humans' natural body odor. That honor lies with the apocrine gland.
The apocrine glands don't develop until puberty, and since they are the glands responsible for body odor, this is the reason that kids don't typically begin to use deodorant or antiperspirant until the onset of puberty.
Apocrine glands are found most abundantly in the axillae, around the genitals and breasts and around the belly button. These glands are responsible for excreting waste, mostly proteins and lipids (fats). This type of sweat doesn't smell inherently, it's when it reaches the skin that an odor is produced. There is native flora (microorganisms like bacteria and fungi found in colonies) on healthy human skin, and these florae set about eating your apocrine sweat when it's excreted onto your skin's surface. As they feed on your sweat, the microorganisms produce the familiar scent of body odor as a byproduct of metabolism.
We've already seen that eating red meat can produce malodorous results. But what are some other foods you might want to avoid if you care to smell nice and pretty?