Soldering lead is a fusible metal alloy used to create a permanent bond between metal work pieces. It must be melted in order to adhere to and connect the pieces together.
This is your basic roll of 0.8mm Soldering Lead with a 60/40 water soluble resin core. This is a good roll of solder leaded for advanced users that should last 6-12 months depending on how often you solder.