The subject of this bachelor thesis is to define and to describe how cloud computing works. Technology is an information society that is constantly advancing. The technology itself is based on the Internet. Furthermore, main part and also the biggest part of this thesis will describe computing in cloud. It will be shown how that computing works, where we can find all the cloud data, how are they being distributed, how much are they available, and in the end, who are the users. Thesis has an introduction, eight headlines and conclusion. The second chapter speaks about computer science, it's history and it's need. Third chapter contains use of content in cloud. Fourth chapter is based on the benefits and the fifth on the disadvantages. Next chapter talks about security threats of cloud computing. Seventh chapter „Use of cloud computing“ contains: private, public and hybrid cloud. In the last chapter we will find the information about popular cloud services. All chapters are sublimated in the conclusion.