Cloud computing allows for centralized data storage and online access to computer resources over the internet. It utilizes large networks of remote servers. There are three main models of cloud computing: public clouds which can be accessed by anyone; private clouds which are for internal use only; and hybrid clouds which combine private and public clouds. The main service models are Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). Cloud computing provides advantages such as flexibility, low costs, easy management of data, and automatic updates, but also poses disadvantages like dependency on providers and security risks.