In the C# unified type system, a value of any type can be treated as an object. This is made possible by the concept of boxing and unboxing.

Boxing

• It is the process of converting a value type to an object.
• CLR puts the value inside a System.Object instance, which is then stored on the managed heap.
• Boxing is implicit.

Example

public void Boxing()
{
    int x = 100;
    object obj = x; // x is boxed into obj
}

Unboxing

• It is the process of extracting a value type from an object.
• Unboxing is explicit.

Example

public void UnBoxing()
{
    object obj = 100;
    int x = (int)obj; // obj is unboxed into x
}