A Recursion is process in which a function or program calling to itself automatically according to values called Recursion of Function or recursive function. Recursion of functions can be simple in which we can use more efficient code for instance, listing or compiling for sets of numbers, strings or other variables through a single reiterated process. Recursion of functions in code often rely on loop setups where the initial variable is called on multiple times while being altered by the loop. Simple examples of a recursive function include the factorial of number where an integer is multiplied by itself while being incrementally lowered. Recursion function and program is used in scientific method for calculating future values.