How do value types and reference types differ in C#?

A value-type variable contains a value, so assignment normally copies that value. A reference-type variable contains a reference, so assignment copies the reference and both variables can refer to the same object. A struct containing reference fields copies those references, not a deep copy of the referenced objects. Storage location is not a reliable definition: value types can be embedded in heap objects or boxed. Choose types according to semantics, size, mutability, and API design rather than assuming value types always live on the stack.