What are the main categories of data types presented in the C# language?

In the C# language, the main categories of data types are divided into two large groups:

1. Value Types

   • Primitive types: int, double, bool, char, float, byte, short, long, decimal, and others.
   • Structures (struct) that can contain multiple value types.
   • Enumerations (enum).

2. Reference Types

   • Classes (class) that store a reference to an object in memory.
   • Interfaces (interface).
   • Delegates.
   • Arrays.

There are also special types:

• string — a reference type for working with text.
• Nullable types (int?, bool?, etc.) — allow value types to accept null.

Example of usage:

int a = 5;          // value type
string s = "text"; // reference type
int? b = null;      // nullable type