Software as a service (or SaaS) moves away from the traditional method of licensing software as a tangible ‘product’ and moves towards the provision of software as a secondary consideration to the provision of the overall service offered under the software. It tends to be a hosted service so that there is no in-premise installation on the client’s own systems. There is less focus on ‘design, acceptance and maintenance’ as distinct phases of a software project and more of a view towards the provision of a more rounded service.
Although SaaS can be modified for specific users, and often is, the premise is that it is more widely available to multiple users in the similar format so that everyone benefits from upgrades and there is no longer a requirement for the client to implement patches as this is done at server level by the proprietor.