I like computers, trains, space, radio-related everything and a bunch of other tech related stuff. User of GNU+Linux.I am also dumb and worthless.My laptop is ThinkPad L390y running Arch.I own RTL-SDRv3 and RSP1 clone.
SDF Unix shell username: user224

Well, Wikipedia: https://en.wikipedia.org/wiki/DVD_region_code#Computer_DVD_drives
Basically same as regions on standalone DVD players. Just a scummy thing to only allow you to play DVDs from your own region, perhaps so that you wouldn't buy them from cheaper countries, or buy them earlier than you're supposed to in your country.
If everything works correctly, then say you buy DVDs from UK, but something new just released in US, but haven't even played in cinemas in UK yet. So you buy it from US... and it shouldn't work.
VLC doesn't care about this, but still, the drive firmware might.
BluRays also have regions
By the fucking way, BluRays have some DRM with revocable keys
https://wiki.archlinux.org/title/Blu-ray#Revoked_Host_key/certificate
So when do you truly own something? When you pirate it. No regions, no DRM, 4k on any device powerful enough.