Soldering is one of the fundamental skills of hardware hacking. It is almost impossible to hack hardware without knowing how to solder. This chapter lists outs the materials required for a soldering process and discusses the method of soldering of wires. Successful soldering depends on cleanliness, heat, steady hands, and timing. Despite appearances, soldering is not just a question of dropping melted solder onto the two things to be joined. The strongest bond results from first melting a thin layer of solder onto each surface (“tinning”), then letting them cuddle up to one another while heating both surfaces to remelt the solder until it commingles. The process is similar to gluing wood: it’s better to saturate the surface of each piece of wood with a layer of glue before assembly, rather than just squeezing out a blob and slapping them together.