Cloud hosting, for example, is the alternative to hosting your website on a single server in your storeroom. If that server goes down, your website is down. However, with cloud hosting you are using multiple servers, if one goes down, your website is still up. Cloud Hosting can be delivered to a client in one of two ways, IaaS (Infrastructure as a Service) and PaaS (Platform as a Service).
PaaS is when the client is provided with software, such as CloudWare, where they can access applications and install hardware straight from the cloud. This is easier to use and more suitable for people that are less technical.
IaaS is for experienced IT professionals. The client is provided with the hardware required to access their cloud hosting. This is used when a client has a complex IT infrastructure.