SaaS is a business application developed and hosted by a service provider. In this model, clients don't have any activity on the environment and the service provider deals with the whole foundation and furthermore the application. The clients are charged in view of the use of the application and its services (pay as you go billing model).
For fruitful cloud selection, you first need to profoundly comprehend your IT environment by recognizing those workloads that will best fit your targeted cloud environment, while additionally giving you a steady profit for your speculation.
The following image will help you understand SaaS:
