Why is cross validation used?

Related questions

1. What is Xgboost used for?
2. Is B tree balanced?
3. What is B+ tree with example?
4. What is cross validation error?
5. What is a surrogate split?
6. What is pruning in R?
7. What is Xgboost Python?
8. What is the difference between B and B+ tree?
9. What is leaf size in decision tree?
10. What is the advantage of decision tree?

Tags

1. #general
2. #unseen
3. #primarily
4. #learning
5. #during
6. #limited
7. #predictions
8. #order
9. #validation
10. #applied
11. #estimate
12. #machine
13. #cross
14. #sample
15. #model
16. #expected
17. #skill
18. #perform
19. #training