are Disc games run through steam?

[MrBlivion]

My cod bo2 game I bought was on a disc there was disc 1 and disc 2 and when I installed the game it installed through steam is this the same for cod bo1 and cod waw? or are they run through windows witch requires the disc to be put in every time you play please need an answer

 

[Cons29]

it depends on the game. some games req the disc some don't. but nowadays, based on my games at least, very few require it