When looping through code, it’s common to use a counter variable. A counter (also known as an iterator) is a variable used in the conditional logic of the loop and (usually) incremented in value during each iteration through the code. For example:

// counter is initialized
int wishes = 0;

// conditional logic uses counter
while (wishes < 3) {

  System.out.println("Wish granted.");
  // counter is incremented
  wishes++;

}

In the above example, the counter wishes gets initialized before the loop with a value of 0, then the program will keep printing "Wish granted." and adding 1 to wishes as long as wishes has a value of less than 3. Once wishes reaches a value of 3 or more, the program will exit the loop.

So the output would look like:

Wish granted.
Wish granted.
Wish granted.

We can also decrement counters like this:

int pushupsToDo = 10;

while (pushupsToDo > 0) {

  doPushup();
  pushupsToDo--;

}

In the code above, the counter, pushupsToDo, starts at 10, and increments down one at a time. When it hits 0, the loop exits.