When and who made the world's first computer.

The first computer was the Electronic Numerical Integrator and Computer (ENIAC), which was built by John Mauchly and J. Presper Eckert at the University of Pennsylvania in 1946. It was a huge machine that weighed 30 tons and used 18,000 vacuum tubes. It was used to calculate ballistics tables for the US Army during World War II.

Here are some other early computers:

* The Zuse Z3 was built by Konrad Zuse in Germany in 1941. It was the first programmable computer that used binary arithmetic.

* The Colossus was built by the British government during World War II to crack German Enigma ciphers. It was the first computer to use electronic valves (vacuum tubes).

* The Harvard Mark I was built by Howard H. Aiken at Harvard University in 1944. It was the first computer to use punched cards for input and output.

These early computers were very primitive by today's standards, but they laid the foundation for the development of modern computers.