cloud computing is a general term for anything that involves delivering hosted services over the Internet. These services are broadly divided into three categories: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). The name cloud computing was inspired by the cloud symbol that’s often used to represent the Internet in flow charts and diagrams.
This essentially means that using idle processing power, memory and storage and other computer resources from the participants of cloud computing. we can explain it like this, most of the Pc’s present doesn’t even 50% of their processing power or memory most of the times. It is all about using this idle resources and using it effectively.
This is mainly useful for those who require very high processing power. Basically they need not go for expensive super computers and they can put their calculations on the cloud and process it at a very cheaper rate.The charge is mainly hourly on in some cases minute by minute basis. This is the wikipedia link for cloud computingcloud_computing.