What exactly is cloud computing? Simply put, cloud computing means that you're accessing data stored on someone else's servers via an Internet connection, rather than those located on-site. Of course, that's a simplistic definition and there is much debate about the "correct" definition of cloud computing.
That being said, the National Institute of Standards and Technology (NIST), widely recognized to be a leader in the cloud-computing field, recently defined cloud computing as follows: "Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction."
In other words, cloud computing allows you, via an Internet connection, to access software or data that is stored and operated on someone else's computer systems. Then, the cloud-computing provider uses shared computer resources, including software and servers, to deliver information and services to the end user.