The progression in hardware representation of a bit of data:
Vacuum Tubes (1950s) - one bit on the size of a thumb;
Transistors (1950s and 1960s) - one bit on the size of a fingernail;
Integrated Circuits (1960s and 70s) - thousands of bits on the size of a hand
Silicon computer chips (1970s and on) - millions of bits on the size of a finger nail.
The progression of the ease of use of
computers:
Almost impossible to use except by very patient geniuses (1950s);
Programmable by highly trained people only (1960s and 1970s);
Useable by just about anyone (1980s and on). to see how computers got smaller, cheaper, and easier to use.