Control Flow is the order in which elements of a computer program - instructions, statements and function calls - are executed and evalutated. In a computer program, actions will run in sequence, one after the other, unless selection or iteration is used. Selection refers to a decison made by the program which determines which part of the code is executed based on the result of some action. Most programming languages use control flow statements such as IF, THEN and ELSE to make these decisions. Iteration is when a set of actions is repeated, eg. in a loop.