• Boxing is an implicit conversion of a value-type to the object type.
  • Boxing a value-type will copy the value on the heap, and place a pointer to the boxed value on the stack.

• Try to prevent boxing/unboxing when possible, use generics or multiple overloads instead.
  • Read Boxing/Unboxing In .NET for performance tests.

int i = 123;
object o = (object)i;

object o = 123;
int i = (int)o;