The update part runs after each iteration body completes. It typically increments or decrements the loop counter to make progress toward the exit condition. Common updates: i++ increments by 1, i-- decrements by 1, i += 2 skips by 2.
You can use any expression that changes variables used in the condition. The update runs after the body but before the next condition check. If the body uses break, the update is skipped and the loop exits immediately without running it.