Keychains are one of the most common souvenir and advertising items. Keychains are commonly used to promote businesses. A standard advertising key chain will carry the businesses name and contact information and often a logo.

In the 1950s and 1960s, with the improvement of plastic manufacturing techniques, promotional items including keychains became unique. Businesses could place their names on promotional keychains that were three-dimensional for less expensive than the standard metal keychains.

Keychains are small and inexpensive enough to become promotional items for larger national companies that might give them out by the millions. For example, with the launch of a new movie or television show, those companies might partner with food companies to provide a character keychain in each box of cereal.

Keychains that currently hold keys are an item that is never long misplaced by the owner. People sometimes attach their keychain to their belt (or belt loop) to avoid loss or to allow quick access to it. Many keychains also offer functions that the owner wants easily accessible as well. These include an army knife, bottle opener, an electronic organizer, scissors, address book, family photos, nail clipper, pill case and even pepper spray. Modern cars often include a keychain that serves as a remote to lock/unlock the car or even start the engine. An electronic key finder is also a useful item found on many keys that will beep when summoned for quick finding when misplaced