We use Boolean values to add logic to the execution of code. For example, we might assign the value true to a variable that tracks the status of a spaceship's firepower:

shipHasDoubleShots = true;

By comparing shipHasDoubleShots to the Boolean literal true, we can then decide how much damage to inflict when a shot hits its target:

if (shipHasDoubleShots == true) {
  // Shoot them with twice the power.
  // This will be reached if the comparison is true.
} else {
  // Shoot them with a single dose.
  // This will be reached if the comparison is false.
}

When the double-shot power runs out, we can set the variable to false:

shipHasDoubleShots = false;

This will cause the larger expression shipHasDoubleShots == true to become false, causing the single-damage-dose script to execute when a shot hits its target.

// userGuess == password will yield either true or false
if (userGuess == password) {
  gotoAndStop("secretContent");
}

And when we ask, "Is the movie clip rotated greater than 90 degrees?" the answer, again, is a Boolean:

// myClip._rotation > 90 will yield either true or false
if (myClip._rotation > 90) {  
  // Fade out the clip if it's rotated past 90 degrees
  myClip._alpha = 50;
}

Many internal ActionScript properties and methods describe the Flash movie environment in Boolean terms. For example, if we ask, "Is the spacebar being pressed?" the interpreter answers with a Boolean: true (yes) or false (no):

// Key.isDown( ) is a function that returns either true or false
if (Key.isDown(Key.SPACE)) {
  // Spacebar is being pressed, so make our spaceship fire
}