The first electronic computer was called the Electronic Numerical Integrator and Computer (ENIAC). It was developed by John Mauchly and J. Presper Eckert at the University of Pennsylvania and was completed in 1945. The ENIAC was a massive machine that weighed over 27 tons and contained over 17,000 vacuum tubes. It was used for military calculations during World War II and was able to perform over 5,000 calculations per second. The ENIAC was a significant breakthrough in computer technology and paved the way for the development of modern computers.