This is an application in which an organization has already invested a considerable amount of time and money. Legacy applications are typically database management systems running on mainframes or minicomputers.

In information technology, legacy applications and data are those that have been inherited from languages, platforms, and techniques earlier than current technology. In the past, much programming has been written for specific operating systems. Currently, efforts are underway to migrate legacy applications to new programming languages and operating systems that follow open or standard programming interfaces. Theoretically, this will make it easier in the future to update applications without having to rewrite them entirely and will allow applications to run on any operating system.

Computer software designed for a specific business purpose, such as a payroll application, which has been in use (deployed) for some time and which forms part of the current business environment.

Older application that cannot be modified to delegate authentication to the single sign-on server. Also known as an external application.

An application in which a company or organization has already invested considerable time and money. Typically, legacy applications are database management systems running on mainframe or mini computers. An important feature of new software applications is their ability to work with legacy applications or import data from them.