Electronic computers
, using either
relays
or
valves
, began to appear in the early 1940s. The
electromechanical
Zuse Z3
, completed in 1941, was the world's first
programmable
computer, and by modern standards one of the first machines that could be considered a
complete
computing
machine.
Colossus
, developed during the Second World War to decrypt
German
messages, was the first
electronic
digital
computer. Although it was
