Cloud computing allows users to access computing resources like servers, storage, databases, networking, software and more over the internet. There are three main cloud service models: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). The document discusses Amazon Web Services (AWS) and Microsoft Azure, two major cloud platforms, and some of their key services like EC2, S3, Lambda, and storage options for AWS and virtual machines, networking, security features for Azure.