Note that the data type sizes don’t need to match, so it’s no problem to have a union with, for example, a 32-bit and a single 8-bit integer, the 8-bit value is simply truncated if needed.

Developers should have a basic proficiency of a language's data types. In this article, Irina Medvinskaya presents an overview of two types of predefined C# variables: value types and reference types.