Can you explain what a temporary value (rvalue) is in the context of programming languages?

In C++, a temporary value (rvalue) is a value that has no name and does not occupy a permanent place in memory, usually the result of an expression or literal. It exists only during the computation and cannot be directly addressed.

Example: in the expression int x = 5 + 3;, the sum 5 + 3 is an rvalue, a temporary value that is immediately used to initialize x.

Unlike an lvalue (a value with an address, such as a variable), an rvalue cannot be modified directly, but with the advent of rvalue references (C++11), resources can be efficiently moved from temporary objects.