Cloud computing provides on-demand access to shared computing resources like networks, servers, storage, applications, and services. It has characteristics like on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured service. The document discusses various cloud service models like SaaS, PaaS, and IaaS and deployment models like private, community, and public clouds. It also covers distributed, grid, cluster, and utility computing concepts related to cloud.