The carabiner is a metal ring equipped with a locking system that allows the insertion of another object, typically a rope. Of different shapes, it has a side that can be opened by means of a lever that can be stopped by a ring nut. It can be made of steel or light alloys. It is used where there is a need to join two elements in a quick, safe and reusable way. A fundamental tool in climbing and mountaineering.

Carabiners are also called connectors, a more correct name, although less used.

Classification of mountaineering and climbing connectors according to EN 12275 and EN 362 standards.

Carabiners are classified into various types that identify the main characteristics and fields of application.

Type B: Basic connector, self-closing, for use in any belay system
Type H: Self-closing connector, generally pear-shaped, intended primarily for dynamic belaying, for example using the Munter hitch (HMS)
Type K: self-closing connector primarily intended for connecting the climber to the anchors on via ferratas (Klettersteig)
Type T: Self-closing connector designed to ensure load application in a precise direction
Type A: Self-closing connector to be connected directly to a specific type of anchors
Type Q: screw-lock connector, with a ring nut that once fully screwed helps support the load (quick link)
Type X: self-closing connector, symmetrical in shape (oval) and intended for example for artificial climbing and pulleys
Type M: Multi-purpose connector, with screw ring, which can be loaded along the major and minor axis