Cloud computing allows users to access computer resources such as software, storage, and computing power over the internet instead of installing and maintaining the resources locally. Resources are provided on-demand from a cloud service provider and paid for only when used. There are three main types of cloud computing: Infrastructure as a Service (IaaS) provides basic computing resources; Platform as a Service (PaaS) offers development tools to build applications; and Software as a Service (SaaS) delivers complete applications to users over the internet. Hadoop is an open-source framework for storing and processing large datasets in a distributed environment across computer clusters.