SaaS is a cloud service where the consumer can access software applications running on the cloud via the Internet. Applications such as Twitter, Office 365, and Flickr are all examples of SaaS. Consumers are charged monthly, weekly, or on an on-demand basis, as per the agreement. With traditional software applications, companies purchase the software at a one-time cost, and install it in their own environment. Unlike on-premise installation, SaaS runs on the cloud, and offers an on-rent model, where customers can register for a service to use software and pay as they use. A good example of SaaS is Office 365.