 Besides the Turing machine, several other models were introduced independently of Turing in the context of research into the foundation of mathematics which resulted in theses that are logically equivalent to Turing’s thesis. For each of these models it was proven that they capture the Turing computable functions. Note that the development of the modern computer stimulated the development of other models such as register machines or Markov algorithms. More recently, computational approaches in disciplines such as biology or physics, resulted in bio-inspired and physics-inspired models such as Petri nets or quantum Turing machines. A discussion of such models, however, lies beyond the scope of this entry.