What is the difference between master vault, replica vault and cache vault?

Hello,

I am a new user of Windchill PDMLink. I am exploring the file vault topic and have read some User Guides, 

1. I read the concepts master vaults , replica vault and cache vaults but in that I am getting confused in the difference

2. So, I am not getting that, when to use master vault, when to use replica and when to use cache vault.

Could anyone guide me further on this

Thank You in advance.

Sumit Patil