Software as a Service, the abbreviation SaaS is used. It is a way of software operation (usually business applications), in which the customer uses the software in the form of service via the Internet. The customer does not need to buy any hardware, neither any other software license, nor take care of the data. The operator provides the customer the hosting of the software on his technical equipment and provides the software in the form of a service, for which the customer pays.
SaaS is typically provided on a contract basis, including the definition of SLA.