Cloud computing is Internet-based computing, whereby shared information, resources, and software, are provided to terminals and portable devices on-demand. It is a rapidly developing and excellent promising technology. Cloud computing is the product of the combination of grid computing, distributed computing, parallel computing, and ubiquitous computing. Cloud Computing model has enabled IT organizations to serve the users globally. It gives the services like Platform as a Service, Software as a Service and Infrastructure as a Service without users being much aware of the details in which the services are provided. …show more content…
The users are not aware of the locations of the files in Clouds. File access seems to them as a single coherent file system.
Benefits of Cloud Computing
• Cheap implementation and reduced maintenance costs • Mobility for a global workforce • Flexible and scalable infrastructures • Increased availability of high-performance applications to small/medium-sized businesses 
Key features of cloud computing
▪ On-demand self-service
The services can be obtained without human intervention and the services are provided by simple logging through user account.
▪ Quality of service
Cloud computing must assure the best service level for users. This is outlined in the service-level agreements must include guarantees on round-the-clock availability, adequate resources, performance, and bandwidth. Any compromise on these guarantees could prove fatal for customers.
▪ Location freedom
This enables users to access using web browser regardless of their location 
▪ Resource pooling
Cloud computing uses multi-tenancy where different resources are dynamically allocated and de-allocated according to demand. From the user’s end, it is not possible to know where the resource actually resides.
▪ Rapid elasticity
Cloud Infrastructure denotes capabilities to provide new services to consumer with different platform specifications. The Cloud models are