Why is swap area needed?

Related questions

1. Can I delete private var VM swapfile?
2. What is the purpose of swap space?
3. How much swap space should I have?
4. What is a VM swap file?
5. What is swap memory?
6. Is swap really necessary?
7. How much swap space should I allocate?
8. What is the swap space in the disk used for?
9. How much swap do I need?
10. What is swap area Ubuntu?

Tags

1. #processes
2. #other
3. #decides
4. #system
5. #unused
6. #operating
7. #amount
8. #happens
9. #memory
10. #inactive
11. #available
12. #space
13. #physical
14. #pages
15. #needs
16. #freeing
17. #moved
18. #active
19. #insufficient