Abstract: Cloud computing is current buzzword in the market. It is paradigm in which the resources can be leveraged on peruse basis thus reducing the cost and complexity of service providers. Cloud computing promises to cut operational and capital costs and most importantly let IT departments focus on strategic projects instead of keeping datacenters running. It is much more than simple Internet. It is a construct that allows user to access applications that actually reside at location other than userís own computer or other Internet connected devices. There are numerous benefits of this construct. For instance other company hosts user application. This implies that they handle cost of servers, they manage software updates and depending on the contract user pays less i.e. for the service only. Confidentiality, Integrity, Availability, Authenticity, and Privacy are essential concerns for both Cloud providers and consumers as well. Infrastructure as a Service (IaaS) serves as the foundation layer for the other delivery models, and a lack of security in this layer will certainly affect the other delivery models.

Keywords: Cloud Computing, IAAS, PAAS, SAAS.