An imperative programming language is one that does things a step at a time, typically manipulating the state of the program in some way at each step. Basic is a good example of an imperative language:

FUNCTION prime% (n!)
  IF n = 2 THEN prime = 1
  IF n <= 1 OR n MOD 2 = 0 THEN prime = 0
  FOR a = 3 TO INT(SQR(n)) STEP 2
    IF n MOD a = 0 THEN prime = 0
  NEXT a
  prime = 1

In this example, we perform each line in sequence until there are no more steps to peform (i.e. we reach END FUNCTION).

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