Pimples are the red color spot in your skin which are made up of Pus and are formed due to blockage in sebaceous glands and infection. Sebaceous gland secrete an oily substance called Sebum. The sebum is released into the skin through hair pores after secretion and it plays the role of lubricating the skin.
However, there are the chances of blockage in hair pores if sebum in secreted more and sebum doesn't come out of the skin and it collected inside the skin. Bacteria,s are developed due to the presence of sebum and they grow fast and cause the infection. Our immune system activates because of the bacteria and white blood cells come together to fight with the bacteria and they eat the dead skin cells as well as bacteria.
The skin get inflammable because of the white blood cells and pus is formed. We see the pimples in the form of Pus. Mostly pimples are appeared on th face as there are more sebaceous glands on our face.