When I was first learning about vacuum tubes and knew nothing, this is the information I would liked to have seen. It exists in various places, but I wanted to collect it together.
This is meant to be an introduction, not an encyclopedia, and it is limited to the kinds of tubes I'm interested in: those used in old radio receivers. There are many other types: radio transmitting, television, computer, photomultiplier, and all sorts of special application types. Anyone interested in those can find further information on them on the internet or in reference books. But the basics here apply to nearly all of them.
I have tried to write each section to stand-alone, but if you are new to this, it would be better to read them in the order presented below.