Australia generally uses a four digit postcode. Each state is designated by a different first number and then the last three indicate the area. This gets a bit more complicated in our territories. The ACT generally begins with 26, the 2 being for New South Wales which surrounds the territory. I am imagine it is similar for Jervis Bay. Northern Territory post codes start with 0.
My own post code is 3004, 3 for Victoria and as I am close to the city, my post code is not far off the Melbourne postcode 3000. Mine denotes St Kilda Road Central and the parallel Queens Road in Melbourne. The capital city post codes generally end in the first number for the state followed by three zeros.
US ZIP Codes work in a similar manner I think. I once had to use a US ZIP Code for some reason in the early days of the internet, and the only one I knew without checking was 90210. Who of my age doesn't know why I would know that?
Japanese postcodes are quite complex. Here is an example. 020-0867. I expect the code is loaded with information, and need to be as street numbers are not necessarily sequential.
English postcodes are very specific. They take you right to the street and to which side of the street you live. Taxi drivers ask for you postcode to take you to your home. At some point, I can't remember, they will ask for the street number, but with often complex street arrangements, it is very helpful for them to know what side of the street you want to be delivered. Here is an English postcode example, NE15 6RL. NE would denote the north east of England, the rest, I wouldn't have a clue.
What is your postcode style where you live and how much does it tell about where you live?