A cloud web hosting service means that each part of your world-wide web presence will be taken care of by an individual server. For instance, your files and databases will be handled by separate machines and since only one kind of processes will run on a server, every single machine will perform better and will use its resources to the fullest. Whether you will get a true cloud service or not also depends on the control panel that you will use to handle your account. Since most control panels were intended to operate on a single server, they are unable to work on a cloud platform regardless of what a given hosting provider could advertise. In the event that one service stops responding, the whole server can go down, so your websites won't be accessible. This is the reason why you should check what service you will actually receive in case you are looking for cloud web hosting before you buy anything.