From a few pieces of the puzzle, such as a name and a ZIP code, data brokers and companies can find an address, the phone number and other personal data.

Here's what to know on how to address an envelope, write a return address, find a zip code, send letters internationally and figure out which stamps are best.

Learn the history and meaning of usps postal codes, why it's called a ZIP code, whether a postal code is a ZIP code, and what ZIP code numbers stand for.