Technology
What is A Turing machine?
A Turing machine is a simple imaginary computer — a tape of symbols and a head that reads, writes, and moves by following rules — invented by Alan Turing to define what 'computation' means. Anything a real computer can compute, a Turing machine can too.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains a turing machine.
Key things to understand
- 1An abstract model: an endless tape, a read/write head, and a table of rules.
- 2Despite its simplicity, it can perform any calculation a modern computer can.
- 3It set the theoretical foundation of computer science in 1936.
- 4It defines the very limits of what is computable.
- 5'Turing complete' means a system is as powerful as a Turing machine.
Frequently asked questions
- Is a Turing machine a real machine?
- No, it's a thought experiment — a mathematical model used to reason about what computers can and cannot do.
- What does 'Turing complete' mean?
- That a language or system can compute anything a Turing machine can, given enough time and memory.
- Why is the Turing machine important?
- It precisely defined computation, founding computer science and revealing that some problems can never be solved by any computer.