Turing Completeness is a concept in computer science that describes a system capable of performing any computation that can be described algorithmically. A system is considered Turing complete if it can simulate a Turing machine, which is a theoretical device that manipulates symbols on a tape according to a set of rules. This means it can solve any problem that a computer can, given enough time and resources. Many programming languages, such as Python and Java, are Turing complete because they can implement any algorithm. However, some simpler systems, like HTML, are not Turing complete because they lack the ability to perform arbitrary computations or maintain state.