SAAS (Software as a Service) is a software delivery model where software is hosted in the cloud and accessed through a web browser. It offers several advantages over traditional software like lower upfront costs, faster deployment, less maintenance requirements, and a pay-as-you-go pricing model. While SAAS adoption is growing due to these benefits, it also presents some disadvantages like less control over the software, potential security issues, and reliance on a stable internet connection. Overall, SAAS delivery has become a successful model due to advances in cloud technology and its ability to simplify software for customers.