A key ring or key ring is a small chain, usually made of metal or plastic, that connects small objects to the key ring. The length of the key chain makes it easier to use than to connect directly to the key ring. Some key chains allow one or both ends to rotate to prevent the key chain from twisting when using items.

The key chain can also be a link between a personal key ring and a belt. It is usually employed by people who need to use the key frequently (such as security guards, prison officials, janitors or retail store managers). The chain is usually retractable, so it can be nylon rope rather than actual metal chain. Chains ensure that they are used to keep keys connected to individuals, reduce the possibility of accidental loss, and save wear on the user's pocket.

Key chain is one of the most common souvenirs and advertisements. Key chains are often used to facilitate business. The standard advertising Keychain will have the merchant name and contact information, usually with a logo.

In the 1950s and 1960s, with the improvement of plastic manufacturing technology, promotional products, including key chains, became very unique. Enterprises can put their name on the three-dimensional promotional key chain, and the price is cheaper than the standard metal key chain.

The key chain is small and cheap enough to be a promotional product of a large national company, which may be presented by millions of people. For example, with the release of new movies or TV shows, these companies may work with food companies to provide personalized key chains in each box of grain.

The key chain currently holding the key is an item that will never be put down by the owner. Key chains are sometimes attached to belts (or belt rings) to avoid loss or to allow quick access to the belts. Many keychains also offer features that owners want easy access to. They include Sabre knife, bottle opener, electronic notepad, scissors, mail list, family photos, nail clippers, medicine boxes, and even pepper spray. Modern cars usually include a key chain that acts as a remote control to lock / unlock the car or even start the engine. The electronic key finder is also a useful item found on many keys. When they are called, it will beep, so that they can be quickly searched when misplaced