The contextual keyword value is used in the set accessor in ordinary property declarations. It is similar to an input parameter on a method. The word value references the value that client code is attempting to assign to the property. In the following example, MyDerivedClass has a property called Name that uses the value parameter to assign a new string to the backing field name. From the point of view of client code, the operation is written as a simple assignment.
Example:-
class MyBaseClass { // virtual auto-implemented property. Overrides can only // provide specialized behavior if they implement get and set accessors. public virtual string Name { get; set; } // ordinary virtual property with backing field private int num; public virtual int Number { get { return num; } set { num = value; } } } class MyDerivedClass : MyBaseClass { private string name; // Override auto-implemented property with ordinary property // to provide specialized accessor behavior. public override string Name { get { return name; } set { if (value != String.Empty) { name = value; } else { name = "Unknown"; } } } }