Software as a Service (SaaS) is a cloud computing model where software applications are delivered over the Internet as a service. Instead of installing and maintaining software on local devices, users access it through a web browser. SaaS providers host and manage the software and underlying infrastructure and handle maintenance, updates, and security. This model offers flexibility, scalability, and cost-effectiveness, allowing users to subscribe to software on a pay-as-you-go basis without worrying about underlying hardware or software maintenance. SaaS is commonly used for various applications, including email, customer relationship management (CRM), and collaboration tools.