This document presents an overview of cloud computing including its basic concepts, deployment models, and service models. Cloud computing allows users to access computing resources like servers, storage, databases, networking, software and more over the internet. There are three main deployment models - public, private and hybrid clouds. The main service models are Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS). The document also discusses the advantages like scalability, cost savings and mobility as well as disadvantages like security concerns, vendor lock-in and internet dependence of cloud computing.