Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In computer science, polynomial time refers to the running time of an algorithm, that is, the number of computation steps a computer or an abstract machine requires to evaluate the algorithm. An algorithm is said to be polynomial time if its running time is upper bounded by a polynomial in the size of the input for the algorithm. Problems for which a polynomial time algorithm exists belong to the complexity class PTIME, which is central in the field of computational complexity theory. Cobham's thesis states that polynomial time is a synonym for "tractable", "feasible", "efficient", or "fast".