How do link shorteners work?

Related questions

1. How do bit ly links work?
2. Are bitly links permanent?
3. Is URL shortener safe?
4. Can bit ly be a virus?
5. Why is my android battery draining so fast all of a sudden?
6. Can you change a bit ly link?
7. Does my phone have a virus?
8. How long does a bitly link last?
9. How do I open a bitly link?
10. How long does bitly link last?

Tags

1. #function
2. #actually
3. #redirection
4. #directing
5. #command
6. #works
7. #requested
8. #shortener
9. #because
10. #enter
11. #sends
12. #server
13. #transmit
14. #called
15. #fetch
16. #redirect
17. #browser