This document provides an overview of cloud computing, including definitions, history, deployment models, service models, how it works, pros and cons, and examples of real-life applications. Cloud computing relies on sharing computing resources over the internet rather than local hardware. It allows users to access software, platforms, and infrastructure virtually through pay-per-use models. Major types include infrastructure as a service (IaaS), platform as a service (PaaS), and software as a service (SaaS). The cloud symbol was used as early as 1977 and cloud computing has evolved significantly since the 2000s with offerings from Microsoft, Amazon, Google, and others.