General term for anything that involves delivering hosted services over the Internet is called cloud computing. Recently this term is often used because the trend of web service providers now is providing services with Infrastructure as a service. These services are broadly divided into three categories: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). These interconnections between providers and the clients is dynamic and the clients or users can have as much or ach little services as they want.
Because of the dynamic system of this services it is called cloud computing. The cloud symbol is often used to represent the internet in flow charts and diagrams, so it inspires the name of cloud computing.
A cloud computing can be either public or private. A public service like Amazon web service provides virtual server instances with particular IP addresses, so it can block of storage on demand. The other example is Google apps service.
The other kind of service is private cloud computing. It limits the user only for particular IP addresses or clients. There are also services that can be used locally that help the users in working with a lager files, offline access to the files and local copy of your files. You can learn more about this services from egnyte.com.