What exactly is cloud computing?

And will it eventually eliminate the need for bulky hardware?What exactly is cloud computing?
Cloud computing is like multiple users are connected to one server and that server acts like a CPU to every user and only that particular person can access his account in it..............its like that ur given a room in a particular house and only you have its keys so that no one else can access ur room......What exactly is cloud computing?
It's a way of doing computing "out there in the cloud". Which of course has to be done somewhere on real hardware, but the cloud computing idea is that you don't care where, and it may change - the DNS name is the same, but the ip address may point to somewhere else and the actual task may be done on a virtual machine that moved to a different location that had cheaper power today.

At least, that's what I understand.

There has to be hardware somewhere. Just maybe not so much in server rooms in small businesses.
One downside is that you are 100% reliant on the internet, and if there's an earthquake and you can't print a prescription because you have no local computing you'd look a bit silly.