When it comes to hosting, cloud architecture refers to using an individual server for every single aspect of the hosting service. Such a setup provides a lot better performance because one machine will be used just for file storage, another just for running databases, and so on, thus different system processes will not run on the same machine. The latter will reduce the chance of system errors substantially and will allow your sites to run faster, not mentioning the greater uptime. When you're looking for such a service, you have to make certain that you will really get it since numerous companies advertise cloud hosting plans, but the control panels they use are not designed to function in a real cloud and can operate only on one server. The problem with using one machine is that if one service goes down or generates high load, the whole server will almost certainly go offline, so your websites will no longer be accessible.