In [[computer science]], '''tail recursion''' (or '''tail-end recursion''') is a special case of [[Recursion_(computer_science)|recursion]] in which theany last operation ofperformed by the function is a recursive call, the [[tail call]], isor returns a recursive(usually callsimple) value without recursion. Such recursions can be easily transformed to iterations. Replacing recursion with [[iteration]], manually or automatically, can drastically decrease the amount of [[Call stack|stack]] space used and improve efficiency. This technique of iterative calculation is commonly used with [[functional programming]] languages, where the [[declarative programming|declarative approach]] and explicit handling of [[state (computer science)|state]] promote the use of recursive functions that would otherwise rapidly fill the [[call stack]].
