Australian Postcodes are four digits long, and written after the name of the city, suburb, or town, and the state or territory:[1]

Mr John Smith

400 Kent Street

SYDNEY NSW 2000

A new postcode system has been introduced in New Zealand for all mail, unlike the old system, 

which was only used for mail sent in bulk. 

It has 1800 four-digit codes with a much finer granularity than the old codes,

with each suburb and PostShop lobby having its own postal code. 

The first two digits specify the area, the third digit specifies the type of delivery (street, PO Box, Private Bag, or Rural delivery),

and the last digit specifies the specific lobby, RD number, or suburb.

In general, Postcodes are not required. 

The exception is Dublin and Cork city where a 1 or 2 digit zone number appears after the name of the city (eg Dublin 2). 

This number is shown after the street name (eg 25 Clare Street 2 = 25 Clare Street, Dublin 2).

 

The format of UK postcodes is generally:

A9 9AA

A99 9AA

A9A 9AA

AA9 9AA

AA99 9AA

AA9A 9AA

Canada

A Canadian postal code is a string of six characters in the format X#X #X#, where X is a letter and "#" is a single digit, with a space separating the third and fourth characters. An example is K1A 0B1, which is for Canada Post's Ottawa headquarters.

The letters D, F, I, O, Q, and U are not used in postal codes. This is because OCR technology is used to sort mail, and these letters can easily be confused for other letters.

Most Information taken from Wikipedia