I am wondering if someone knows how the zip code works. Just the 5 digits ones?

Does the 2 starting digits are the ones that the search site uses to locate near by cities/towns?I am wondering if someone knows how the zip code works. Just the 5 digits ones?
maybeI am wondering if someone knows how the zip code works. Just the 5 digits ones?
The ZIP code is the system of postal codes used by the United States Postal Service (USPS). The letters ZIP, an acronym for Zone Improvement Plan ...

The United States equivalent of what most other countries' postal systems call postcodes, post codes, or postal codes. ...I am wondering if someone knows how the zip code works. Just the 5 digits ones?
depends on the site now doesn't it.