A "postcode" is a set of numbers and letters used to identify a specific location or area for the purpose of mail delivery. It helps to make sure that letters and packages are sent to the correct place. Full definition
This basically means lower, or higher wages for doing the same work, depending on where you live; a kind of postcode lottery for pay if you like. (politics.co.uk)
If you're living in postcodes areas NE19, NE48 - 49 and are eligible for assistance, you could get your cat neutered for # 5 at participating vets. (cats.org.uk)
He explained that, the new digital addressing system, has unique postcodes for every location in Ghana, saying, «We have been able to put together 16.1 billion addresses: every five by five metres square apart in Ghana has a unique address.» (citifmonline.com)