In it's simplest form an algorithm is the systematic sequential process by which input tokens or numbers are transformed into output tokens or numbers in a finite number of steps. The word algorithm is derived from the name of the ninth century Persian mathematician Abu Ja'far Mohammed ibn Mûsâ al-Khowârizm. The precise formulation of the concept of a general algorithm dates only from the 20th Century. The most important specification of an algorithm is in terms of the concept of a Turing Machine.