A soldering iron or gun is a hand tool used for soldering two metal conductors. It has universal application especially in the electronic industry, where very small and thin conductors have to be joined or soldered to a terminal on a printed circuit board. It is an indispensable tool in an electronic assembly or repair shop.
Modern irons are electrically operated. Very early models used to be plain copper block pointer with a wooden handle with the pointer being heated on an open fire. Present day production lines of high volume have special soldering methods using large ovens for jointing component leads. For the common use, soldering irons used are mostly in the range of 20 to 60 Watts.
When choosing a soldering gun or soldering iron for your electronic projects, the primary consideration should probably be how many watts the soldering iron is. For most projects that involve electronic components you can safely purchase a soldering iron that is between 20 and 60 watts with the average around 50 watts.