Minimum privilege for Backup and replication

Dear All Postgresql Users,
I am new to pgsql. I have an installation on my Ubuntu 18.04.

Now, my question is -
What is the Minimum Privilege of a pgsql Backup or Replication user?

I know how to do it for mysql but not pgsql.?? I begin to switch to pgsql 
v11 from mysql v5.7 after knowing it many nice features.?? Mysql seems 
very old-fashioned.?? Oracle and IBM DB2 are just too $$$ to me.

Thanks for your opinions.

Timmy