Charles Babbage (26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer. Considered by some to be "father of the computer", Babbage is credited with inventing the first mechanical computer that eventually led to more complex electronic designs, though all the essential ideas of modern computers are to be found in Babbage's Analytical Engine. His varied work in other fields has led him to be described as "pre-eminent" among the many polymaths of his century.

Parts of Babbage's incomplete mechanisms are on display in the Science Museum in London. In 1991, a functioning difference engine was constructed from Babbage's original plans. Built to tolerances achievable in the 19th century, the success of the finished engine indicated that Babbage's machine would have worked. The idea of mechanically calculating mathematical tables first came to Babbage in 1812 or 1813. Later he made a small calculator that could perform certain mathematical computations to eight decimals. 

Then in 1823 he obtained government support for the design of a projected machine, the Difference Engine, with a 20-decimal capacity. Its construction required the development of mechanical engineering techniques, to which Babbage of necessity devoted himself. In the meantime (1828–39), he served as Lucasian Professor of Mathematics at the University of Cambridge. During the mid-1830s Babbage developed plans for the Analytical Engine, the forerunner of the modern digital computer.

In that device he envisioned the capability of performing any arithmetical operation on the basis of instructions from punched cards, a memory unit in which to store numbers, sequential control, and most of the other basic elements of the present-day computer. 

In 1843 Babbage’s friend mathematician Ada Lovelace translated a French paper about the Analytical Engine and, in her own annotations, published how it could perform a sequence of calculations, the first computer program.  The Analytical Engine, however, was never completed. Babbage’s design was forgotten until his unpublished notebooks were discovered in 1937. In 1991 British scientists built Difference Engine No. 2—accurate to 31 digits—to Babbage’s specifications.

According to en.wikipedia