I see everyone saying JDM this and JDM that

Is it just the black wheel bright car scheme? the flat paint look?

And why is everyone like Im selling XXX JDM wheels, when they arent even in japan (not literally) Like Falken wheels or something liek that

Arent JDM like Volks, Spoon, Buddy Club, Mugen, Gram Lights etc. stuff that is expensive over here, but dirt cheap there?(and i know they are, ive seen pictres lol )

just wondering