Software as a service (or SaaS) is a part of cloud computing. It refers to a model in which software and IT infrastructure are delivered as an integrated service by an external provider. The SaaS software is usually accessed via an internet browser. Saas software is typically paid using a subscription fee while there are no maintenance and support costs since the web-based application is hosted, supported, updated, and maintained by the service provider. This is the main difference between SaaS and traditional license models: instillation, IT infrastructure, and upgrades do not have to be handled by the customer but are managed by the service provider. Therefore, the customer does not pay a software license but a usage fee.