Parameter: A parameter is a variable in a function or procedure declaration that represents an argument. It acts as a placeholder for the actual value that will be passed in when the function/procedure is called.
Return Value: A return value is the result or output produced by a function or procedure after it has executed. It can be used as an argument for another function call.
Default Argument: A default argument is an optional value specified in a function or procedure declaration. If no corresponding argument is provided during the call, the default value will be used instead.