Are european versions of pc games region free on cd-dvd

Do PC games( CD or DVD rom game disc) have region codes like ntsc or pal or are they region free. That is can games made in europe install and play on your pc in the US using your dvd rw drive or cdrw drive. I am not talking about xbox or playstation which are not region free.

some software including games look at your region settings and wont run unless you change to the right region this is not very common though, other than that no, there is no difference to games they should run fine