ZIP - Zone Improvement Plan
These codes are used by the postal service department to effectively send the mail to its recipient. In United States area postal codes are known as "Zone Improvement Plan" codes which are used by the United States Postal Service (USPS) for area identification.
In India area postal codes are known as Postal Index Number (PIN) codes, not the zip codes as in the US. You might heard people using ZIP codes instead of PIN codes even in India. In India, we have a six digit PIN code that represents different areas of a large city or sometimes a complete village.
Also See: Full Form of PIN Code