The time will come to prove that computing will one day be the 5th utility after water, electricity, gas and telephony. That will provide the basic level of computing services such as supporting files needed to run any type of software. It aims to share data, calculations, and services transparently among users. It became a hot issue concern to advantages those are reduction in costs, increase in business flexibility and/or provide business continuity. This paper defines the cloud computing, cloud deployment model, cloud delivery model and its benefits.