Backward compatibility

Backward compatibility is the ability of newer hardware or software to run products made for an earlier version. It preserves access to older programs, files, devices, or interfaces after an upgrade.

Application binary interface: An application binary interface specifies how compiled programs interact with an operating system, library, or processor. Keeping an older ABI lets previously compiled programs run on a newer system.
Windows NT: Windows NT is a family of operating systems that includes modern desktop and server versions of Microsoft Windows. Its compatibility subsystems have supported many programs written for earlier Windows environments.
Forward compatibility: Forward compatibility is the ability of an older system to handle data or behavior introduced by a newer system. It reverses the direction of compatibility: older systems face newer products.
Technical debt: Technical debt is the future cost of maintaining or changing a system after choosing a faster or simpler implementation. Compatibility constraints can preserve outdated design decisions and increase maintenance costs.
Emulation: Emulation reproduces the behavior of one computer system using another system. An emulator can recreate an older platform so its software runs on newer hardware.
Wine: Wine is a compatibility layer that runs many Windows applications on Unix-like operating systems. It translates Windows interfaces rather than requiring a Windows installation.
Breaking change: A breaking change is a modification that makes existing users, integrations, or data incompatible without adaptation. It marks the point where an update stops preserving earlier behavior.
Software obsolescence: Software obsolescence occurs when software becomes difficult or impossible to use, maintain, or obtain. Compatibility support can delay obsolescence when platforms and formats change.
Virtualization: Virtualization creates software-defined versions of computing resources, including machines and operating systems. A virtual machine can preserve an older operating system environment alongside newer software.
PlayStation 2: The PlayStation 2 is Sony's video game console released in 2000. Its early models could play most games made for the original PlayStation.

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