Explain Postal Code Concept

I need a clear, concise write-up that answers the question “What is a post code?” and outlines its everyday uses. Please cover how postal codes help with customer location verification, service-area zoning, and shipping cost calculation, but keep the focus on explaining the concept itself rather than implementing any technical validation—no format or database checks are required.

Deliverable: a well-structured document (about 500 – 800 words) that defines postal codes, traces their global variations, and illustrates their practical benefits with real-world examples.