What is the difference between following and followers on twitter?

Related questions

1. Can you start a tweet with a hashtag?
2. How do you find what is trending on twitter?
3. How can you tell if someone is following you back on twitter?
4. Does Twitter make money?
5. Should I use twitter?
6. How do you follow a hashtag on twitter?
7. Can you track a hashtag on twitter?
8. Can you follow a hashtag on twitter?
9. How do I Unsuspend my twitter account?
10. Does twitter save search history?

Tags

1. #tweet
2. #their
3. #respective
4. #following
5. #share
6. #follower
7. #metric
8. #accounts
9. #followers
10. #opted
11. #content
12. #follows
13. #other
14. #feeds
15. #account
16. #tweets
17. #twitter
18. #every
19. #users
20. #someone
21. #instagram