What are the types in C# language and how are they used?

In C#, types define what kind of data a variable can store and what operations are permissible with that data. Types are mainly categorized into two groups:

• Value Types — store data directly. Examples: int, double, bool, structures (struct). They are usually located on the stack.
• Reference Types — store a reference to the memory area where data is held. Examples: classes (class), arrays, strings (string). They are located on the heap.

Using types allows the compiler to check the correctness of operations, manage memory, and ensure type safety. For example:

int number = 10; // value of type int
string text = "Hello"; // reference type string

// You can create your own types using classes and structures
class Person {
    public string Name;
    public int Age;
}

Person p = new Person { Name = "Ivan", Age = 30 };

Types also influence behavior when passing parameters to methods (by value or by reference) and memory management.