What is the exact Deal with Maintenance DB ?

Hiii,

I trying to understand what is the exact usage of Matenance DB
"postgres" ...

,I think It is a template like "template1" ... and If we want to
generate a database we create new one from "postgres" template...

However I cant do it, but I can create a new databse from template1 ...
I really dont understand the functionality of "postgres" ...

If I create a connection from template 1, and create another connection
from the conneciton 1, It clones the DB on the first conneciton to the
second ...

If I drop the DB from one connection, then the second conneciton looses
the DB as well ...


in what circumtances, we may need two conneciton on the same Posqgresql
server ?...

sorry I am really confused about that...