This paper describes the concept of cloud computing, service models, application models, and aspects of cloud computing . Cloud Computing is a new form of electronic business that is rapidly growing and is just about to experience its peak. The need for innovation and the improvement of information systems has led to its formation. It is based on the principle that a user for their business rents computer resources from service providers instead of buying them. Depending on your needs, a user can rent one of three basic models: infrastructure as a service (IaaS), platform as a service (PaaS) or software as a service (SaaS). Advantages such as savings and the ability to access information at a time when the user needs it regardless of location and time, are the reason for the active growth of computer clouds in information technologies. Security is very important in cloud computing, but there is no solution that guarantees absolute security. Data is stored in multiple locations, and likely to be lost is very small.