Software as a Service (SaaS) is a software licensing and delivery model in which software is accessed online via a subscription, rather than being bought and installed on individual computers. SaaS applications are hosted on external servers and accessed through the web, eliminating the need for extensive hardware and enabling users to access the software from anywhere with an internet connection. This model is widely used in business and digital marketing for CRM tools, analytics platforms, content management systems, and more, offering scalability, accessibility, and cost-effectiveness.