What does default(object); do in C#?

Question

Googling is only coming up with the keyword, but I stumbled across some code that says

MyVariable = default(MyObject);

and I am wondering

Answer 1

Another good use of default(T) is when compiler can't determine returning type, like in here

class X
{
    public int? P {get; set;}
}

// assigning in code

var x = new X();

// consider coll["key"] returns object boxed value
// data readers is one such case
x.P = myReader["someColumn"] == DbNull.Value ? default(int?) : (int)myReader["someColumn"];