What is Backward Compatible (Backward Compatibility)?

Developer explains why full PS5 backward compatibility is impossible

Nintendo Switch 2 backward compatibility is far from perfect as Nintendo relies on new methods to play old games  - VideoGamer

Sony still working out the PS5 backwards compatibility details

A ressonable discussion on PS5 backwards compatibility and modes

Sony patent hints at cloud-based backwards compatibility for PS5

PS5 backwards compatibility list: Which PS4 games will be backwards compatible with PlayStation 5?

Ninja Gaiden 2 is now backward compatible for Xbox One

Here are the first 100 backward-compatible Xbox 360 games