Everyone is talking about “cloud computing.” But what is cloud computing ?

What is cloud computing ?

Cloud computing : the group of networked elements providing services need not be individually addressed or managed by users; instead, the entire provider-managed suite of hardware and software can be thought of as an amorphous cloud.

Cloud computing is an information technology paradigm that enables ubiquitous access to shared pools of configurable system resources and higher-level services that can be rapidly provisioned with minimal management effort, often over the Internet.

Cloud computing is the the use of various services, such as software development platforms, servers, storage and software, over the internet, often referred to as the "cloud."
In general, there are three cloud computing characteristics that are common among all cloud-computing vendors:

1.    The back-end of the application is completely managed by a cloud vendor.

2.    A user only pays for services used  memory, processing time and bandwidth, etc.