What are the differences between a class and a structure in programming?

Main differences between class and struct in C#:

• Data type: Classes are reference types, structs are value types.
• Storage: Classes are stored on the heap, structs on the stack (unless they are part of a class).
• Inheritance: Classes support inheritance, structs do not.
• Constructors: Structs cannot have parameterless constructors, classes can.
• Passing: When passing a struct to a method, a copy is created; when passing a class, a reference is passed.

Example:

struct Point {
    public int X, Y;
}

class Person {
    public string Name;
}

Point p1 = new Point { X = 1, Y = 2 };
Point p2 = p1; // copy
p2.X = 3;
// p1.X will remain 1

Person person1 = new Person { Name = "Ivan" };
Person person2 = person1; // reference
person2.Name = "Peter";
// person1.Name will also change to "Peter"

The choice between class and struct depends on the task and requirements for performance and semantics.