Three important paradigms are described below. The first computers were used to solve mathematical problems that arose in large military and scientific projects. In this kind of work, algorithms are permanent and data is transient. Each algorithm represents a large investment in scientific and programming effort. The algorithm is kept on, or near, the computer.
Users bring their problem to the computer, run the algorithm, and then leave with their results.
Programming languages that are primarily designed to express algorithms are called procedural languages. In the 1950's large businesses started using computers. Banks put their customers' checking accounts on computers. Insurance companies put their policies on computers. And firms of all kinds used computers to run their accounting and payroll operations.