What is boxing and unboxing?

Explanation

• Boxing is the process of converting a value type to the type object or to any interface type implemented by this value type. When the CLR boxes a value type, it wraps the value inside a System.Object and stores it on the managed heap.
• Unboxing extracts the value type from the object.
• Boxing is implicit
• Unboxing is explicit.

Performance

In relation to simple assignments, boxing and unboxing are computationally expensive processes.

• When a value type is boxed, a new object must be allocated and constructed.
• To a lesser degree, the cast required for unboxing is also expensive computationally.

Follow up questions

• How does boxing and unboxing impact performance?
• How to avoid the performance hit of boxing/unboxing?
• What is the difference between stack and heap?