Method anatomy

A method is a named, reusable block of behavior. The header tells you everything:

public static double average(int a, int b)
//        ↑static  ↑return type ↑name     ↑parameters

• Parameters are the inputs — typed placeholders filled by the call.
• Return type: what comes out. void means "returns nothing".

public static double average(int a, int b) {
    return (a + b) / 2.0;
}

return does two jobs: hand back the value and exit immediately. Code after a taken return never runs — which is why early-return validation works:

public static String sign(int n) {
    if (n < 0) {
        return "neg";
    }
    return "non-neg";
}

A void method can still return; early — bare, with no value. Arguments are matched by position and type: average(3, 4) fills a = 3, b = 4. Too few, too many, or mismatched types = compile error.