This allows users to run software applications and store, edit and retrieve data over the internet from large networks of remote web servers rather than on users’ own computers. 
The cloud refers to remotely-hosted data centres or web servers. 
Rather than relying on computer products from corporate servers or desktop PCs, applications and services created in this new "cloud" are delivered over the internet and often accessed through a simple web browser, e.g., google docs. 
Online cloud computing offers cheaper services. 
Also, services depend on a fast broadband connection and a fast, efficient and secure browser. 
If you have a Hotmail, Yahoo or Gmail e-mail account you are already using one type of cloud computing service. Similarly, social networking services such as Facebook and online photo sharing services such as Flickr rely on so-called Web 2.0 technology and cloud computing.