Cloud computing is the delivery of computing resources as a service over a network. It allows users to access shared computing resources, software, and data on demand. There are three main types of cloud computing: Infrastructure as a Service (IaaS) which provides virtual machines and storage; Platform as a Service (PaaS) which provides development tools; and Software as a Service (SaaS) which provides applications. Cloud computing provides advantages like flexibility, cost savings, and ability to access resources from anywhere.