SaaS can be explained as "software deployed as a hosted service and accessed over the Internet."
SaaS offers substantial opportunities for organizations of all sizes to shift the risks of software acquisition, and to move IT from a cost center to being a
proactive, value-producing part of the enterprise.
SaaS applications take advantage of the benefits of centralization through a single-instance, multi-tenant architecture, and provide a feature-rich experience competitive with comparable on-premise applications.
SaaS application being offered directly or as an intermediary party (aggregator), by compiling SaaS offerings of multiple vendors and offering them as part of a unified application platform.
In contrast to the one-time licensing model commonly used for on-premise software, SaaS application access is frequently sold using a subscription model, with customers paying an ongoing fee to use the application.
On the technical side, the SaaS provider hosts the application and data centrally—deploying patches and upgrades to the application transparently, and delivering access to end users over the Internet through a browser or smart-client application.