Anything that is not an [[L-Values|L-value]] is an R-value - Right hand side of assignment expression - Literal - Temporary intended to be non-modifiable ```cpp int x {100}; // 100 is R-value int y = x + 200; // (x+200) is R-value string name; name = "Frank"; // "Frank" is R-value int max_num = max (20, 30); // max(20, 30) is R-value ``` References can be made to [[L-Values|L-values]], not R-values - also applies to [[Pass by Reference|pass by reference]]