backward compatibility : Java Glossary

If old data files can be used by a new version of a program, that is called backward compatibility. Java JVMs (Java Virtual Machines) are all backward compatible.Java version 1.5 can still run version 1.0 class files. Watch out. Many people are confused by the terms backward compatibility and forward compatibility and use them interchangeably. Backward compatibility is the ordinary kind. Forward compatibility is much trickier to arrange.

Backward compatibility also refers to the ability run old software on new computers, operationg systems and and JVMs. Sometimes vendors such as Microsoft deliberately destroy backward compatibility to force customers to buy new software.