What is observable and promise?

Related questions

1. What is promises and observable?
2. What is the use of observable in angular 4?
3. Why do we use observable in angular?
4. What is the RxJava?
5. Does angular do observable?
6. What is observable in RxJS?
7. What is an observable in angular 2?
8. What is switchMap in RxJS?
9. What is the use of observable in angular2?
10. Why should I use RxJava?

Tags

1. #allows
2. #handle
3. #where
4. #languages
5. #events
6. #observable
7. #stream
8. #callback
9. #preferred
10. #matter
11. #event
12. #called
13. #multiple
14. #doesn
15. #because
16. #often
17. #features
18. #promise
19. #provides