What's the difference between type definition and type reference?

Question

I am reading the book CLR via C# by Jeffrey Richter.

In Chapter 23(23.3.2), it says "A System.Type object represents a type reference(as opposed to a type definition)."

What do the type reference and type definition mean here?

Answer 1

The author is contrasting System.Type with System.TypeInfo. From the documentation:

A TypeInfo object represents the type definition itself, whereas a Type object represents a reference to the type definition.

The System.TypeInfo for a class can only be instantiated if the assembly that implements the class (the type definition) is loaded or loadable. To instantiate a System.Type, the only requirement is that the current program contains a reference to the implementing assembly.

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