Church's Thesis, also known as the Church-Turing Thesis, is a principle in computer science and mathematics that proposes a definition of what it means for a function to be computable. It suggests that any function that can be effectively calculated by a human using a step-by-step procedure can also be computed by a Turing machine, a theoretical model of computation. The thesis is named after Alonzo Church and Alan Turing, who independently developed concepts of computability in the 1930s. While it is not a formal theorem that can be proven, it serves as a foundational idea in the study of algorithms and the limits of computation, influencing fields such as theoretical computer science and mathematical logic.