By public cloud we understand an ecosystem or infrastructure composed by space and applications of different functionalities (word processing, spreadsheet, presentations¦). When using these applications we generated archives, that are stored in that space. This service is offered by suppliers and at the disposal of all that one that wants to use them or to buy them.
They can be of payment or gratuitous and the information is in an infrastructure outside your control. They are not in your servers, but in those of the supplier (Google, Microsoft, etc.). This way, for example, Google can have your account of gratuitous Cloud in a machine or servant that shares thousands of accounts more. On the other hand, this servant can physically be in California (the USA), outside the control of the RGPD of the European Union, which can cause legal implications on the treatment of the data stored in him.
This surroundings are not negative in itself, but it can not be appropriate for a company that need to have its data under control at any moment and within the European Union. The public and gratuitous clouds are well for personal use, but when we used them for the enterprise management and data storage, it can be recommendable the creation of own virtual surroundings, in servers property of the company and under protocols of security that responds to the needs of the company and the legal frame in which the company develops its activity.
Shelp this, the question is not public cloud or deprived cloud, but perhaps a combination of both, what is called hybrid cloud, so that the company or the professional can benefit from the advantages of each, mainly considering that the public one offers many possibilities to cost zero.