Polite Imperative Form...

In the section "5.8 Imperatives",  in the lesson it says; The imperative tense only applies in three forms:
tu - you (familiar)
voi - you (plural)
noi - we/us

Well, I thought there is also a polite form for the imperative tense. Is this wrong?
I saw this before, people can use it like. "Parli per favore." "Fermi per favore."
Which in "-are" verbs, usage is the opposite of present tense...  
tu - parla
Lei - Parli

Which in "-ire and -ere" verbs
tu - prendi
Lei - prenda...
tu - vieni
Lei - venga 

Hi serhangordon,

What you see in the lesson are the familiar (informal) imperatives only. The formal imperative is a little trickier and it's covered in later lessons, namely in 8.9 (Directions, here: https://members.rocketlanguages.com/members/italian/lessons/1272/8-9-directions) and in the lessons that are dedicated to the subjunctive case (Module 20). This is because the formal imperative uses the same endings of the subjunctive case, and this can be tough for natives as well!

Hope this helps!
Lucia