a hypothetical device with a set of logical rules of computation: the concept is used in mathematical studies of the computability of numbers and in the mathematical theories of automata and computers.

Origin of Turing machine

after Alan M. Turing (1912–54), English mathematician, who described such a machine in 1936

a hypothetical universal computing machine able to modify its original instructions by reading, erasing, or writing a new symbol on a moving tape of fixed length that acts as its program. The concept was instrumental in the early development of computer systems

An abstract model of a computing device, used in mathematical studies of computability. A Turing machine takes a tape with a string of symbols on it as an input, and can respond to a given symbol by changing its internal state, writing a new symbol on the tape, shifting the tape right or left to the next symbol, or halting. The inner state of the Turing machine is described by a finite state machine. It has been shown that if the answer to a computational problem can be computed in a finite amount of time, then there exists an abstract Turing machine that can compute it.