Answer Description

Software as a Service (SaaS) is a cloud model that replaces locally used applications and programs with a cloud based, centrally hosted equivalent. An example of this is using Microsoft Office 365's web based email and calendar solutions instead of installing the Outlook program locally. Typically SaaS applications are served as web solutions compatible with any modern browser.

Wikipedia

Software as a service (SaaS ) is a software licensing and delivery model in which software is licensed on a subscription basis and is centrally hosted. SaaS is also known as on-demand software, web-based software, or web-hosted software.SaaS is considered to be part of cloud computing, along with several other as a service business models. SaaS apps are typically accessed by users of a web browser (a thin client). SaaS became a common delivery model for many business applications, including office software, messaging software, payroll processing software, DBMS software, management software, CAD software, development software, gamification, virtualization, accounting, collaboration, customer relationship management (CRM), management information systems (MIS), enterprise resource planning (ERP), invoicing, field service management, human resource management (HRM), talent acquisition, learning management systems, content management (CM), geographic information systems (GIS), and service desk management. SaaS has been incorporated into the strategies of nearly all enterprise software companies.