Legacy software program

A legacy software program (also called a "legacy system") is an application software package typically developed 10-35 years ago for mainframe and/or mini computers. These systems were designed and developed (1) when memory and disk space was available in limited quantities for each system/application, (2) when memory and disk space were prohibitively expensive, and (3) before the creation and industry acceptance of key software engineering tools and techniques that make software more maintainable and less error prone.