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legacy applicationAn application that was written for an earlier operating system or hardware platform. For example, mainframe applications were legacy apps when the world embraced client/server networks. Windows 3.1 applications were legacy apps when Windows 95 was introduced. Windows 7 applications running in Windows 8 are called legacy apps.
Any business software that is not Internet enabled in some form is sometimes considered a legacy application.
They Hang Around
Although many are eager to embrace the newest and latest, there is an investment in older software, which is sometimes substantial. Legacy applications tend to remain in use far longer than anyone predicts. In some cases, they thrive, such as mainframe applications. Even DOS applications are running today under 32-bit versions of Windows (see XyWrite). See legacy system.