Unlike shared grids, which are based on open source technologies, clouds are a proprietary technology. Only the resource provider knows exactly how their cloud manages data, job queues and security requirements.
To understand exactly how cloud computing works, let’s consider that the cloud consists of layers -mainly the back end layers and the front end layers. The front layers are the parts you see and interact with. When you access your profile on your Facebook account for example, you are using software running on the front end of the cloud. The back end consists of the hardware and the software architecture that delivers the data you see on the front end.
Clouds use a network layer to connect users’ end point devices, like computers or smart phones, to resources that are centralised in a data centre. Users can access the data centre via a company network or the internet or both. Clouds can also be accessed from any location, allowing mobile workers to access their business systems on demand.
Applications running on the cloud take advantage of the flexibility of the computing power available. The computers are set up to work together so that it appears as if the applications were running on one particular machine. This flexibility is a major advantage of cloud computing, allowing the user to use as much or as little of the cloud resources as they want at short notice, without any assigning any specific hardware for the job in advance.