An alloy is a mixture of chemical elements of which in most cases at least one is a metallic element, although it is also sometimes used for mixtures of elements;

The soft solder used for welding and plumbing is alloy of Tin and Lead. The mixture of tin and lead creates a eutectic alloy, meaning it has a lower melting point than either metal alone, making it easy to work with and join metal parts together without excessively heating the base material, making it ideal for delicate applications like plumbing joints and electrical connections.