Definition   ITERATION is the act of repeating a construct,  or a slight variation on a construct,  again and again in some controlled fashion.

Definition   A WHILE statement is a repetition construct inwhich the thing being repeated is repeated while some condition is true.

Definition   A COUNTER CONTROLE LOOP is a repetition construct which is characterized by aprieri knowledge of how many times the instruction block is to be run.

Definition   A DATA CONTROLE LOOP is a repetition construct which is governed by ``metadata'' the data processed.

Definition   INCREMENTAL PROGRAMMING is a programming methodology wherein on develops a program by writing a sequence of programs with the following properties:

1. The first program in the sequence performs some essentially trivial task,  but one which is fundamental to completion of the ultimate task.
   
2. the last program in the sequence performs the task of ultimate interest.
   
3. Each successor program performs a task only marginally more elaborate than its predecessor.