Cloud computing is the concept of the division of the program environment which uses the Internet as a platform and enables applications and documents sent out from all over the world to be stored and kept on particular servers. The classification of cloud computing models NIST bases on two main criteria: delivery and application criteria. According to the delivery criterion there are three models: software, infrastructure and platform as a service, while according to the application criterion there are models that are: private, public, hybrid and community cloud. Nowadays, the great majority of IT corporations provide some kind of cloud computing. The most famous ones are Google, Amazon and Microsoft. The biggest advantage in cloud computing is the “pay as you go” option. Users do not have to pay for their equipment but instead pay for using cloud computing. The main disadvantages are insecurity and unavailability. Security is very important for companies so when they transfer their applications or build new applications in the cloud, they must have a security model which is consistent, elaborate and will facilitate the development, prevent mistakes and keep the value they invested. Security risks, threats and breaches in the system can occur in many different ways and from various locations so many companies take comprehensive approach in IT security control and management. The future vision of computing in the cloud consists of 4 phases. The first phase is the use of cloud computing services instead of investing in your equipment, the second is internal migration into the cloud, the third is the reduction in the number of private clouds and the last phase is the transition to the computing. Cloud computing can be of help to companies in their efforts to improve their electronic business which will result in positive changes in the company's business performance.