There is also another type of postal code, the ZIP + 4 code. According to unitedstateszipcodes.org, the ZIP + 4 was established in 1983 and identifies an even more specific location within a ZIP code.

Why ZIP codes have 5 numbers — and what they each mean By Barbara Tasch 2015-06-30T16:24:11Z ...

You probably know your ZIP code by heart but do you know what it stands for? It turns out that the five or so digits point to some pretty specific information about you and where you live in the ...