A bobby pin is a type of hairpin. In British English, it is known as a hair grip, grip, or kirby grip. It is a small pin

Pin

A pin is a device used for fastening objects or material together.Pin may also refer to:* Award pin, a small piece of metal or plastic with a pin attached given as an award for some achievement...

 or clip, usually of metal or plastic, used in coiffure

Hairstyle

A hairstyle, hairdo, or haircut refers to the styling of hair, usually on the human head. The fashioning of hair can be considered an aspect of personal grooming, fashion, and cosmetics, although practical, cultural, and popular considerations also influence some hairstyles.-History of...

 to hold hair in place. Typical bobby pins are plain and unobtrusively colored, but some are elaborately decorated or jeweled. A bobby pin is a double-pronged hair pin that slides into hair with the prongs open and then the flexible prongs close over the hair to hold it in place.