Hey guys! I stumbled on this great CGP Gray Video about how Postal Codes work. For those of you like me who love system design, the video is fun on its own merits.

The Hidden Pattern in Post Codes https://youtu.be/1K5oDtVAYzk?si=jeRrvWubgWFlld0C

But why post it here?

In the video he explains how the optional 4 character code at the end of your post code helps get your envelopes sorted more quickly when present. All it takes is a few minutes finding the code and adding it to your address on deckbox!