Konrad Zuse built the Z3, widely regarded as the world's first working programmable, fully automatic digital computer, in 1941.
Zuse was a German civil engineer who wanted to automate lengthy structural calculations. He built a sequence of machines, beginning with the mechanical Z1 and the relay-based Z2, before completing the Z3 in Berlin in 1941.
The Z3 used electromechanical relays and represented numbers in binary floating-point form. Programs were supplied on punched film, and the machine could perform arithmetic operations automatically. It was destroyed in an Allied bombing raid in 1943, so historians rely partly on surviving descriptions and later reconstructions.
The Z3 is not usually called the first electronic computer because its switching elements were electromechanical. Some historians also distinguish it from earlier special-purpose machines, but its programmable, automatic, digital design makes it a landmark in computing history.