The safety pin is a variation of the regular pin which includes a simple spring mechanism and a clasp. The clasp forms a closed loop to properly fasten the pin to whatever it is applied to and covers the end of the pin to protect the user from the sharp point.

Safety pins are commonly used to fasten pieces of fabric or clothing together. Safety pins, or more usually a special version with an extra safe cover, called a nappy or loincloth pin, are widely used to fasten cloth diapers (nappies), or modern loincloths. They're preferred as their safety clasp, while remaining an ingestion hazard, prevents the baby from being jabbed or pricked. Safety pins can be used generally to patch torn or damaged clothing. They can also be used as an accessory in all kinds of jewelry including: earrings, chains, and wristbands. Sometimes they're used to attach an embroidered patch. Safety pins are divided into numbered size categories. Size 3 pins are often being used in quilting and may be labelled for purchase as a "quilting pin." Sizes 4 and larger may be called "blanket pins" and deemed acceptable as kilt pins for informal dress, depending upon design and appearance.