Used to express a previous statement in a different way or from a different perspective; that is to say

Used to introduce a well-known proverb, meaning "as the saying goes" or "as the common proverb says".

To lay the unpleasant facts on the table first; to give a fair warning before things get difficult.

perfect or really good; beyond reproach or criticism

Used to resume a previous topic of conversation after a digression; anyway