Body odour 
       Body odour is a general term for what happens to sweat and other skin secretions when they are acted upon by naturally occurring bacteria. Sweat or perspiration is a salty liquid, which oozes out of the pores in our skin. Two types of glands produce sweat, the "eccrine" glands and the "apocrine" glands. The "eccrine" glands are dispersed throughout the body but are concentrated in the armpits, palms of the hands, soles of the feet, and the forehead. When the body is overheated - from hot weather, physical exertion, or fever - the "eccrine" glands help regulate body temperature by expelling a solution of water and salts that cools the skin.

                 The "apocrine" glands are concentrated in the armpits and around the groin. These glands develop during puberty and have nothing to do with temperature regulation; instead, they respond to such conditions as sexual arousal, nervousness, and anger, as well as to heat and exertion. The sweat they produce is rich in organic substances that attract bacteria and produce a strong odour. Other reasons could be the purely the 'faulty lifestyles' or 'emotional stresses' like in ovulation or menopause when the hormones trigger the "apocrine" glands to produce the characteristic smell.


Causes

      Not only sweat glands but also sebaceous glands and apocrine sweat glands produce substances contributing to body odor. Sebaceous and apocrine become active at puberty. This as well as many apocrine glands being close to the sex organs points to a role related to mating. In humans the armpit regions seem more important than the genital region for body odor which may be related to human bipedalism. The genital and armpit regions also contain springy hairs which help diffuse body odors.
Factors such as food, drink, and diseases can affect body odor.An individual's body odor is also influenced by lifestyle, gender, genetics, and medication.
Body odor is influenced by the actions of the skin flora, including members of Corynebacterium, which manufacture enzymes called lipases that break down the lipids in sweat to create smaller molecules like butyric acid. These smaller molecules smell, and give body odor its characteristic aroma. Propionic acid (propanoic acid) is present in many sweat samples. This acid is a breakdown product of some amino acids by propionibacteria, which thrive in the ducts of adolescent and adult sebaceous glands. Because propionic acid is chemically similar to acetic acid with similar characteristics including odor, body odors may be identified as having a vinegar-like smell by certain people.[citation needed] Isovaleric acid (3-methyl butanoic acid) is the other source of body odor as a result of actions of the bacteria Staphylococcus epidermidis, which is also present in several strong cheese types.