SaaS is also known as “multi-tenant cloud” or “software on demand”. SaaS provides access to software via the Internet. Its pay-as-you-go method allows a customer to use software on an as-needed basis, without needing to install it or purchase a license. SaaS applications can be accessed securely by multiple customers, each of whom typically pays a subscription usage fee.
When using the SaaS model, each client’s data is accessible only to themselves. Since this is a single instance of software, customization is limited, but it often can be personalized through profiles or system settings.
The diagram below explaining the cloud service models of SaaS.