A small, typically metallic, coiled "double loop" device used to securely hold, organize, and manage multiple keys together.

Key Aspects of Key Rings:
Structure: Most commonly a split ring, which is a single piece of metal coiled into a double loop, allowing keys to be slid onto the ring.
Function: Beyond holding keys, they serve as organizers and, through attached fobs or charms, a form of self-expression or branding.
Types: Standard split rings, chain rings, and specialized quick-release or locking rings, such as those by Orbit Key.
Evolution: Modern versions often include functional items like bottle openers, flashlights, and USB flash drives.
History: The modern split ring was popularized in the late 19th century, with inventor Samuel Harrison often credited with early designs. 
Key rings are essential everyday carry (EDC) items that keep keys accessible and secure, often acting as a connector for more decorative keychain components.