Welcome to the Forum and the World of Duplicate Questions.
This subject has been covered a couple of times before (understatement of the year) but as I now, after looking for it five or six times, know where some of the official documentation is - here is a
place for you to start reading. Maybe it will help. Maybe not.
When you get to the 'not' stage, come back with more questions and perhaps a few words about yourself fo an Introduction.