All About Through Hole Technology
Although not as popular nowadays, through-hole components were dominant for decades. IBM pioneered the through-hole part along with printed circuits and the technology of how to put leaded components through the circuit. Before this everything was all wire wound. Since the evolution of SMT technology has largely replaced the through-hole technology construction method, its popularity has gone way down and today are used mostly for making interconnections between board layers or when a stronger connection to the pcb is needed.