See the below image for the Pants parts with labels diagram. There are fifteen different parts of jeans pant you can identify from the following anatomy analysis of jeans pant. Waist Band. Belt Loop. Button. Fly. Watch Pocket. Front Pocket. Back Pocket.
Belt loops are added with jeans pant so that belt can fix on it and hold the pant where we supposed to hold. There are five to seven loops are there in jeans pants. But most of the designers prefer five loops onto the waistband. The button is used to close the top of the fly of jeans pant.
The waistband is made from denim fabric which surrounds our waist when we wear jeans pant or any other pants. On this waistband, we basically wear a belt to fit properly. A pair of jeans pant contains only 1 waistband on it. Belt loops are added with jeans pant so that belt can fix on it and hold the pant where we supposed to hold.