How are postcodes decided?

Related questions

1. Are all ZIP codes 5 digits?
2. What is a postcode district?
3. Can two houses have the same postal code?
4. How does the UK postcode system work?
5. Why do postcodes change?
6. How do I change my zip code to postal code?
7. What does my postcode mean?
8. Are postal codes house specific?
9. Can a postcode cover more than one street?
10. What is the biggest postcode area?

Tags

1. #right
2. #digit
3. #single
4. #premises
5. #postcode
6. #street
7. #working
8. #letter
9. #represents
10. #represent
11. #digits
12. #district
13. #within
14. #first
15. #system
16. #letters
17. #generally
18. #hierarchical
19. #following