Iteration is a characteristic of certain algorithms or computer programs in which a sequence of one or more algorithmic steps are performed in a program loop. It is distinguished from the repetitive technique called recursion.
Here is an example, in pseudocode:
a = 0 for i = 0 stepby 1 until 3 a = a + i print a /* "6" is printed */
A process which is repeated again and again it know as a reiterative process. Reiteration is often used in order to converge on the final result when starting with an educated guess.
See also: Iterative and Incremental development -- iterator -- Iterative method -- Nash embedding theorem