Just like with NPN and PNP transistors, there are N-FETs and P-FETs. N-FETs are like NPN transistors – the gate pin needs to have higher voltage than the source pin for the FET to open.

The first transistor was about half an inch high. That's mammoth by today's standards, when 7 million transistors can fit on a single computer chip. It was nevertheless an amazing piece of technology.

So What Was the Transistor Good For? Transistors may have been useful to the phone company and to a handful of scientists building computers, but that wasn't enough to build an industry.