Why head tag is used in HTML?

Related questions

1. What are html5 layout tags?
2. Where does the body tag go in HTML?
3. Can I have two body tags in HTML?
4. Why title tag is used in HTML?
5. What are html5 tags?
6. What are the empty tags?
7. What does Article tag do in html5?
8. What is aside tag in HTML?
9. Why article tag is used in html5?
10. What is pre tag in HTML?

Tags

1. #often
2. #mandatory
3. #about
4. #scripts
5. #information
6. #writing
7. #title
8. #metadata
9. #things
10. #referred
11. #links
12. #document
13. #contain
14. #files
15. #which
16. #specific
17. #includes