Rückwärtskompatibilität

Rückwärtskompatibilität, in English backward compatibility, is the ability of a system to interoperate with earlier versions of itself or with data produced by earlier versions. It aims to preserve functionality for users when software, hardware, or formats evolve, enabling newer implementations to process or run older content without modification.

In computing, backward compatibility spans software APIs, binary interfaces, file formats, and hardware standards. Achieving it can involve stable application programming interfaces (APIs) and application binary interfaces (ABIs), documented versioning policies, and explicit support for older data. Compatibility layers, emulation, and polyfills are common techniques that translate older behaviors for newer environments, while data format specifications may include tolerance for older encodings or metadata.

Strategies used to promote backward compatibility include versioned interfaces, deprecation schedules, and clear transition paths. Adapters and shims can map deprecated calls to current implementations, while archival formats and converters help preserve access to legacy data. When designing systems, engineers weigh the benefits of supporting old capabilities against the cost of added complexity, performance overhead, and potential security risks.

Examples of backward compatibility appear across domains: software libraries maintaining support for older function signatures; operating systems providing drivers for previously supported hardware; and data formats that remain readable by newer tools. While backward compatibility enhances user trust and ecosystem stability, it can slow innovation and complicate maintenance. In many cases, organizations balance long-term support with orderly deprecation, offering migration paths and interim compatibility solutions.

See also forward compatibility, deprecation, versioning, and compatibility layers.