How does IsDisposed really work?

There have been number of blogs, SO questions telling you how to know if the object is already disposed. E.g. using IsDisposed property available with some classes.

I want to know:

• Assuming IsDisposed is returning true, if the object is already disposed, how come we are allowed to call a IsDisposed property on it?
• If we can access its property, how can we say that object is dead or thrown away or disposed? (Are you not referencing it by calling its property?!)

UPDATE # 1:

I have follow up questions after couple of answers stating that "Disposed does not mean object is dead; it just means that any unnanaged resources it's holding are freed up.":

• Does that mean that Disposed is not saying that this object is disposed?
• If the Disposed object itself is not dead, why do we get ObjectDisposedException ? (Does not it mean that this object cannot be used any longer? )