What does a canonical tag do?

Related questions

1. What is Hreflang in HTML?
2. What does the rel attribute do?
3. What is meant by canonical representation?
4. What is rel and href?
5. How important is Hreflang?
6. What is Hreflang?
7. What is the use of rel?
8. How do I fix canonical problems?
9. What is link rel alternate?
10. What is canonical path?

Tags

1. #engines
2. #specific
3. #search
4. #problems
5. #master
6. #multiple
7. #telling
8. #caused
9. #content
10. #represents
11. #using
12. #appearing
13. #prevents
14. #duplicate
15. #identical
16. #canonical