Cloud Hosting

What’s the difference between cloud computing and Hosting on a online web server?
Could somebody please explain to me what cloud computing is in laymen’s terms?
To put it simple, Dedicated servers have limited resources. There is a limit on the number of processors or hard drives that you can put into a Dedicated Server. You cannot run 100k websites from one dedicated server.
But you can do that with a cloud hosting, as you can add the same server hardware to a cloud, and the power of the cloud will just go on increasing. The resources of all the servers and computers in the cloud are shared, and therefore, a reseller Hosting Company can virtually Host billions and billions of sites in what would look like just 1 server, but which actually is a cloud of several hundreds of servers.
Cloud hosting in a very large scale is highly profitable since management costs would come down, however, the hardware costs would just remain the same.
What is Cloud Hosting?