What are historical uses of computers?

Answer 1

The first use of computers in the modern sense of the word was for military and scientific applications ... ballistics calculations, cryptography, and that branch of "science" that overlapped with "military", i.e. the Manhattan project. As they ceased being bleeding-edge research and costs dropped, very large companies began using them for business purposes (various forms of what I, as a non-accountant, would refer to vaguely as "bookkeeping").