I always explain it like this:

Bitcoin is simply a virtual unit that is impossible to counterfeit and has a finite total of only 21 million in existence.
The creation of this finite unit supply is controlled by mathematics, not people. And the mathematical framework also acts as the actual payment network.

It is because of these characteristics Bitcoin emulates all of the properties of money used in trade.

But what makes it so special is that it is 100% politically neutral. No government can control it, shut it down, or manipulate its supply thus, Bitcoin's value is determined completely by the free market making it the best and fairest form of money in the world.