What is a structure? Is it a value or reference type? Where is memory allocated? What are the boundaries of effective use of structures?

In C#, a struct is a user-defined value type that stores data directly, rather than a reference to it. Memory for structs is usually allocated on the stack if they are declared as local variables, or inside an object if the struct is a class field.

Main features and boundaries of using structs:

• Structs are suitable for small and simple objects, such as representing coordinates, colors, or dates.
• They do not support inheritance (except for implementing interfaces).
• Due to copying by value, large structs can incur overhead when passed around.
• It is recommended to use structs when the size does not exceed about 16 bytes and when value-copy semantics are appropriate.

Example of a struct:

public struct Point
{
    public int X;
    public int Y;

    public Point(int x, int y)
    {
        X = x;
        Y = y;
    }
}