Parameters and return value

<script language="javascript" type="text/javascript">
         function Add(a, b) { 
            var sum = a + b; 
            return sum;
         }
      </script>
  
 <input type="button" id="btnTest" onclick="alert(Add(5, 6))" value="Sum" />

A function can accept one or more parameters and may or may not return value