Cloud computing is a style of computing that leverages internet-based services for scalable and flexible computing resources, allowing users to access applications and data without local installation or management. It includes models such as Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS), enabling cost-effective access to technology through utility or subscription-based billing. The concept encompasses a range of applications and challenges, including security and legal considerations, as it transforms traditional IT infrastructure into a global, shared resource.