PS4 Games Will Play On PlayStation 5, Sony Says
https://www.gamespot.com/articles/ps4-games-will-play-on-playstation-5-sony-says/1100-6466282/
PS5: Release Date, Price, Reveal, Games, Specs, Backwards Compatibility, And More
https://www.gamespot.com/articles/ps5-release-date-price-reveal-games-specs-backward/1100-6466357/
Cerny [Mark Cerny, lead system architect] also confirmed the PS5 will be backwards compatible with PS4 games, as the two consoles are built upon similar internal architectures. This will be welcome news for those who were disappointed by the PS4's lack of backwards compatibility with PS3, PS2, and PS1 games.
SIE president Jim Ryan told GameSpot sister site CNET backwards compatibility and cross-gen are important for the PS5 to help players have a seamless transition.
"Whether it's backwards compatibility or the possibility of cross-generational play, we'll be able to transition that community to next-gen," he said. "It won't be a binary choice about whether you have to be either on PlayStation 4 or next-gen to continue your friendship."
In yet more welcome news, PS4 games will even run faster than they do on your current console, in part because the PS5 will contain a solid state drive, as opposed to hard drives that current consoles ship with. Cerny has demonstrated a load screen from Insomniac's Spider-Man taking less than a second on a PS5 development kit, compared with 15 seconds on a PS4 Pro.
A bit on "cross-generational play":
Ryan also spoke about the ability to start games on PS4, continue them on PS5 and then eventually take all that progress back to the PS4 as part of a “cross-generational play” feature that saves data to Sony servers and preserves your game state.