I recently bought a powerful gaming laptop and I want to buy a couple of games for it (Quantum Break and Ori and the Blind Forest, if someone wonders).

Preferrably physically, as they're cheaper and I like to collect the cases.

My question is as the title says, how do games work on DVD? Are they only needed for the installation or do you need to have the disc in your drive all the time?

If it's the latter, does it read the game data from the disc or it's only for DRM purpuses? More accurately, will I have a performance bottle neck if I use a not so fast external optical drive for playing games?

Sorry for the noob questions

They are only needed for installation and will work without the disc provided u aren't buying really old pc games. You will probably need internet access depending on the game tho.

Any game that requires you to activate it through steam will not require the disc after it is installed, in some cases titles literally just have a steam installer on the disc, and you have to download the entire game anyway.

Awesome, thank you guys!

30% of the physical boxes I buy are "code in a box"
30% of the games are > client installer on a dvd + download
40% are the game on 1 or multiple DVD's and steam/origin or battle.net or uplay in combination with steam needed

I haven't bought a physical PC game in a really long time, because at some point the games started to have activation keys, rendering the physical copies essentially worthless. What good is a physical copy when all it has is a key to active on a service, after which the physical copy is useless?

Anyway, as far as I know, very often there's a Steam (or similar) key which you use, after which you don't really need the physical copy for anything. It's just like buying it digitally, only you end up with a useless physical copy as well. In some cases, there's actual game data on the disc, and in some cases, just an installer for the service (i.e. Steam, Origin etc.) the game requires. In any case, I think it's very rare for a game to NOT require activation on some service.

So it all depends on the game. The vast majority of games will come with some kind of activation code. Enter your code into steam (or Battle.net, or Origin, or UPlay, or whatever), and then either download the game or install it from the disc. Your disc will remain pristine, and your case will look lovely on your shelf. Some games come with literally a DVD case with nothing in it but a code (I'm looking at you, Dark Souls 2). And some games will still require that you have the disc in. Not many, but they exist. I have a physical PC version of Pier Solar that required it be inserted. And I believe some of the Indie Box games require the disc be in. But don't quote me on that because I always use the free steam key for all my Indie Box games.