If you purchase select games for the Playstation 3 and would like to have those said games for the Playstation 4, Sony is going to help you out.
For $9.99 you can download the PS4 digital copy of your PS3 game, open to be played at any time.
Should you have purchased Assassin's Creed IV: Black Flag, Call of Duty Ghosts, Watch_Dogs, or Battlefield 4 for your PS3, you need to keep the voucher found inside. This voucher is what holds the code that you redeem on your PS4. It can be redeemed before (and without) the PS4, so I recommend it doing it immediately.
Also, the PS3 disc itself needs to be inserted into the PS4 for it to play.
Which, I don't quite understand. So the PS3 disc gets inserted into the PS4, then data is downloaded, and the PS3 disc is now a PS4 one? So, PS4 data is stored on the disc already? How does all that new PS4 information work on the PS3 disc? I'm not a tech geek like that, so the only explanation I have is Magic.
It's has to be Magic.
If you don't purchase the physical copy and go digital instead, you'll receive a code. Simple.