Can we get an official explanation on what parrying is?

[localareanetwork]

There is literally nothing in game or on Google that isn't about the thing removed in 4.0 besides a Reddit thread that vaguely explains it along with PLD Block. And THAT is just that you randomly have a chance to block physical damage...

But for those that are curious and don't actually know... (because recently I told someone who started playing in HEAVENSWARD about it for the first time who never noticed it, and I started playing in Shadowbringers!)

All classes can parry and have the same rate of doing it (20% chance), it lowers the damage of any random physical attack by 15%. Why is this never explained anywhere in the game or on any official websites?