Too bad widescreen TVs didn't debut at 21:9 like they should have.  Now we have two different screen ratios both called 4K: the original, DCI standard at 4096x2160; and the TV marketing shenanigans at 3840x2160... which isn't even close to 4K.  Used to be just called 2160p or UHD.

It's like 4G for cell phones.  They slap the label on everything, even stuff we used to call 3G.  It's now magically called 4G because... reasons.