In computer science, having value semantics (also value-type semantics or copy-by-value semantics) means for an object that only its value counts, not its identity. If the concept is fully applied, value semantics implies immutability of the object.
The concepts that are used to explain this concept are extensionality, definiteness, substitutivity of identity, unfoldability, and referential transparency.
References
Value semantics Wikipedia(Text) CC BY-SA