"Backward Compatibility" (Backward Compatibility) is a computer technology term that refers to a system (which can be a software application, computer hardware, computer protocol, etc.) that is compatible with an older version of the system.
Specifically, programs or data written using older versions of software can run seamlessly on newer versions of software if the newer versions of the software are backward compatible. Changes and enhancements do not break existing functionality and can continue to be used without modifying existing data and code. Likewise, if a hardware device is backward compatible, it should be able to accept older hardware devices or interfaces.
Backward compatibility is an important design consideration, especially for systems with a large number of users and a large amount of pre-existing data and code. If a new version of the system is not backward compatible, it may require extensive modification and recoding when upgrading, which may result in a lot of work and cost.