Question

In C#, what makes a field different from a property, and when should a field be used instead of a property?

Answer 1

Properties expose fields. Fields should (almost always) be kept private to a class and accessed via get and set properties. Properties provide a level of abstraction allowing you to change the fields while not affecting the external way they are accessed by the things that use your class.

public class MyClass {     // this is a field.  It is private to your class and stores the actual data.     private string _myField;      // this is a property. When accessed it uses the underlying field,     // but only exposes the contract, which will not be affected by the underlying field     public string MyProperty     {         get         {             return _myField;         }         set         {             _myField = value;         }     }      // This is an AutoProperty (C# 3.0 and higher) - which is a shorthand syntax     // used to generate a private field for you     public int AnotherProperty { get; set; }  } 

@Kent points out that Properties are not required to encapsulate fields, they could do a calculation on other fields, or serve other purposes.

@GSS points out that you can also do other logic, such as validation, when a property is accessed, another useful feature.