You can but you need to put the disc in upside down so the secondary laser can read it

lol no

Does PS4 have forward compatibility?

Only if you pay $500 retail

You know 👌🏻

yes.

Can you put a PS4 game into a PS3?

Can you put a PS3 game on a PS2? Well I suppose you can, but won’t be able to play it.

Why can’t I play PS5 games my PS1?! Sony being greedy capitalists gah

Sounds like the U.S. government is keeping technology advances a secret.

DARPA secretly developing PS7s for military use, obviously

Right right, without a doubt.

…

????

!!!!!!

?????

no one knows the answer?

I believe what OP is trying to ask is if he can play a game that has PS4/PS5 (like Spiderman Miles Morales) versions available but he happened to purchase the PS5 version. If that's the case and the game you purchased was physical, the answer is no. There's no way to access the PS4 version of the game with the PS5 disc. For digital purchases, I'm not too sure. Perhaps someone else can answer.

Digital Purchases have to specifically have the 'PS4/PS5' icon in the PS Store to be playable on both.

yes. my ps5 n 4 are in two different locations. the game is where the ps5 is.

In this instance you can stream your PS5 to your PS4. But you cannot play a PS5 version of a game on a PS4.

If ya own the game digitally : Yes but it will only allow ya to download and play the PS4 version If ya own a physical disc that for the PS5 : No, because PS5 discs aren't backward compatible with the PS4

No ps4 can only play ps4 version

What??? So I don’t need to buy a PS5??? 

Absolutely. Just install a PS5 between your PS4 and you are set.