Soldering is a process of “permanently” and conductively connecting electrical components. Usually, they are soldered to the Printed Circuit Board (PCB). There are two basic types of electrical components. Through Hole Technology (THT) approach uses components with long legs (connectors) which are put through the PCB and then soldered. More sophisticated electronics use Surface Mounted Devices (SMD) which are much smaller, have no legs, and are soldered directly to the PCB.