A soldering iron is a hand-held tool used to join two or more electronic components together by melting solder, a metal alloy. It typically consists of a metal tip that heats up when electricity flows through it, allowing the user to apply heat directly to the parts being joined. Soldering irons come in various wattages, with higher wattages providing more heat for larger components. These tools are essential in electronics for creating reliable connections in circuits. Proper use of a soldering iron requires skill and practice, as overheating can damage components, while insufficient heat may result in weak joints.