Cloud computing is the on-demand delivery of IT resources—including servers, storage, databases, networking, software, analytics, and intelligence—over the Internet ('the cloud') with pay-as-you-go pricing. Instead of buying, owning, and maintaining physical data centers and servers, organizations can access technology services on an as-needed basis from a cloud provider like Amazon Web Services (AWS), Microsoft Azure, or Google Cloud.
The concept of cloud computing dates back to the 1960s with the idea of an 'intergalactic computer network' proposed by J.C.R. Licklider. However, the modern term and its widespread commercial adoption began in the early 2000s, notably with the launch of Amazon EC2 in 2006. It marked a shift from the traditional on-premise IT model to a utility-based model.
Cloud computing has become the backbone of the digital economy. It powers everything from streaming services and social media to enterprise applications and big data analytics. It enables startups to scale rapidly without heavy upfront investment and allows large enterprises to innovate faster. The three main service models are Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS).