Questions about endl

Hi, everyone, I am a starter of c ++ programming.
I would like to know about 'endl'
1. What is that?
2. How does it function?
3. How to use?
4. Effects of using it?

Answers are extremely appreciated, thank you.

http://www.cplusplus.com/reference/i...pulators/endl/
http://www.cplusplus.com/forum/beginner/7350/

Thanks alot.