While

One way to make a loop in code is to use while.

void main() {
int x = 5;
while (x != 0) {
    IO.println(x);
    x--;
}
}

You write while followed by a condition inside of ( and ) and some code inside of { and }.

while (CONDITION) {
    <CODE HERE>
}

If the condition evaluates to true then the code inside of { and } will run. After that code runs, the condition will be evaluated again. If it still evaluates to true then the code { and } will run again.

This will continue until the code in the condition evaluates to false.

void main() {
int glassesOfMilk = 99;
while (glassesOfMilk > 0) {
    IO.println(
        glassesOfMilk + " glasses of milk left"
    );

    glassesOfMilk--;
}
}

If a loop is made with while we call it a "while loop."¹

1. "We called him Tortoise because he taught us." - Lewis Carroll ↩