In computability theory, a collection of data-manipulation rules (an instruction set, programming language, or cellular automaton) is said to be Turing Complete when the rules followed in sequence on arbitrary data can produce the result of any calculation.
In computability theory, a collection of data-manipulation rules (an instruction set, programming language, or cellular automaton) is said to be Turing Complete if and only if such system can simulate a single taped Turing Machine. In practice, Turing-completeness means that the rules followed in sequence on arbitrary data can produce the result of any calculation.