Cloud computing means using multiple server computers with a digital network, as they were one computer. 



How it works

A cloud user needs a device such as a desktop computer, smart phone, or other computing resource with a web browser to access a cloud system via internet.

Risks

Cloud computing's users are exposed to risks such as:

1) International and economic problems. 
2)Data migration problems when changing the cloud provide.

Technical description

The National Institute of Standards and Technology  provides a concise and specific definition:
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.