A computer is a device capable of performing a series of repetitive arithmetic or logical functions far more quickly than the human brain. The earliest computers were designed to solve complex mathematical equations. British mathematician Charles Babbage conceived such a machine, called the Analytical Engine, in the 19th century. Many variations of analog, or mechanical, computing devices were built during the first half of the 20th century, and were used for such tasks as computing torpedo tracking in submarines and controlling bombsights. The growing study of electronics in the late 1940's led to the invention of the digital computer. The first all-electronic computer, containing 18,000 vacuum tubes and capable of hundreds of multiplications per minute, was built in 1946. Continuous advances in electronics since this landmark event rapidly reduced the size and increased the speed and efficiency of computers. Today, computers are commonplace, and are used in virtually every field of endeavor. Significant advances in computer technology continue to take place at an amazing pace.