Page "Backward compatibility" Paragraph 3

In programming languages, backward compatibility refers to the ability of a compiler for version N of the language to accept programs or data that worked under version N-1.

By this definition, if previous versions ( N-1, N-2, etc.

) were also backward compatible, which is often the case, then, by induction, version N will also accept input that worked under any prior version after, and including, the latest one that was not backward compatible.

However, in practice, features are often deprecated and support is dropped in a later release, which is yet thought of as backward compatible.