One of the hot topics in computer technology is software as a service, in which vendors host applications on the Internet and provide them via a browser to users, who perform and store their work online. Users thus don't have to worry about developing, hosting, updating, or maintaining applications or storing data. Several vendors have taken the SaaS concept a big step further and now offer platform as a service systems. PaaS systems are generally hosted, Web-based application-development platforms, providing end-to-end or, in some cases, partial environments for developing full programs online. They handle tasks from editing code to debugging, deployment, runtime, and management. In PaaS, the system's provider makes most of the choices that determine how the application infrastructure operates, such as the type of OS used, the APIs, the programming language, and the management capabilities. Users build their applications with the provider's on-demand tools and collaborative development environment.