It happpens when an oily substance  called sebum clog pores.  pimple usually occurs on face ,neck,back and shoulders. it is due to sweat and sebaceous gland
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1) The secretions of sweat and sebaceous glands are very active .
2) Because of increased activity of these glands adolescents get pimples on the face .
3) Owing to extra secretions sometimes a distinctive odour is also produced fro their bodies .
4) Don't squeeze the pimples . They make your face appear with black spots . 
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