Solder is a metal used to join two pieces together. It is a fusible metal alloy which has a melting point below the pieces you are looking to join. You heat it with a soldering iron until it melts and use the liquid metal to make the join which holds firm when the solder cools. Soft solder is typically thought of when solder or soldering is mentioned, with a typical melting range of 90 to 450 °C (190 to 840 °F). It is commonly used in automotive repair, electronics, plumbing, and assembly of sheet metal parts, but can be used for a wide range of activities - even stained glass! When used for electronics it is particularly good as it creates a conductive bond between two pieces, perfect for electrical circuits.