What does iPhone 5s' 64-bit processor actually do?

*Please Read*

I don't want everyone just quickly responding with "It's pointless!"
I have heard people say before that this 64-bit chip is rather meaningless now but in the future it might mean something good. What exactly does that mean? I mean, you'd think Apple wouldn't advertise the fact that it has a 64-bit chip if it was completely and utterly useless!

So, what is 64-bit? What does it do? How will it benefit the iPhone? How long do we have to wait until we see a difference?

The main benefit of 64 bit - it allows you to use more then 4GB of RAM.

But the iPhone 5S has less then 4GB, which is why people are saying it's not that great. Several years from now phones will have over 4GB of RAM.