Software as a service (or SaaS) is a way of delivering applications over the Internet-as a service. Instead of installing and maintaining software, you simply access it via the Internet, freeing yourself from complex software and hardware management.
SaaS is typically deployed via the cloud whereby u pay a subscription fee, implement and use the software. Some examples include Salesforce.com, Workday, and Compose.
In short, SaaS provides a real solution to businesses struggling with the traditional and inefficient in-house systems.