Prefix ++x increments before using the value. Postfix x++ uses the value then increments. In isolation, both produce the same result: x increases by one. The difference appears in expressions.
int a = 5; int b = a++; assigns 5 to b, then increments a to 6. int c = ++a; increments a to 7, then assigns 7 to c. Prefer prefix in loops: for (int i = 0; i < 10; ++i).
Both work, but prefix avoids creating a temporary copy of the old value.