Blind rivet, also known as a pop rivet, is a mechanical fastener used to join two materials together when access to the backside of the workpiece is impossible. It consists of a rivet body and a mandrel (stem) that, when pulled by a special tool, deforms the body and creates a permanent, strong connection. Blind rivets are highly versatile and are used in applications like aircraft, boat building, and HVAC systems where speed, ease of installation, and secure, one-sided fastening are crucial.