# US ZIP+4 codes ## Overview 2Checkout offers support for both standard and ZIP+4 ZIP codes. ## Standard US ZIP codes The standard ZIP code notation used by the United States Postal service uses five digits to identify a delivery area. An example of a standard US ZIP code is **90210**. ## ZIP+4 codes In addition to the classic five-digit ZIP codes used in the United States, 2Checkout also supports the use of ZIP+4 add-on ZIP codes, important when shipping physical goods. The ZIP+4 system uses the basic five-digit code together with four additional digits to identify a geographic segment located within a five-digit delivery area. The segment can be a city block, a group of apartments or other mail receiving units that could benefit from the use of an additional identifier. An example of a ZIP+4 ZIP code is **99577-0727**. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.2checkout.com/payment-link/checkout-links-and-options/us-zip+4-codes.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.