Solder is a metal alloy that is used to join two or more metal components together. Solder typically consists of a mixture of tin and lead, although lead-free solders are also available. Solder is typically used in electronic assemblies to create permanent, electrically conductive joints between circuit board components and other electrical contacts. Accessories for soldering include items such as soldering irons, soldering stations, flux, and desoldering tools. Batteries are a type of electrical power source that converts chemical energy into electrical energy. Batteries are commonly used in portable electronic devices, such as laptops and smartphones, as well as in larger applications such as electric vehicles and backup power systems.