What is a property and how does it differ from a field?

A field is a variable declared directly in a class. A property is a member with get and set accessors that looks like a field to callers but runs code, enabling validation, computed values, lazy loading and encapsulation.

public class Person {
    private int _age;                  // field
    public string Name { get; set; }   // auto-property

    public int Age {                    // full property
        get => _age;
        set => _age = value >= 0
            ? value
            : throw new ArgumentOutOfRangeException();
    }

    public string Display => $"{Name} ({Age})"; // get-only
}

Auto-properties let the compiler generate the backing field. Prefer properties in public APIs so you can change the implementation later without breaking binary compatibility or callers.

init accessors allow assignment only during object initialisation, supporting immutable objects. Expression-bodied get-only properties are concise for computed values. Properties can also have different access levels, such as public string Id { get; private set; }.