YOU YOU YOU

Contractions are combinations of words made into one.  It is usually done for convenience or sound.  Some of the most common ones include the word you or not.  For example; you have (you've), you will (you'll), you are (you're) and is not (isn't), was not (wasn't) are not (aren't).  These are all acceptable in speech and writing.

Unacceptable are contractions of bad English.  For example;  you all (y'all).  It used to be a Southern colloquialism but can be heard almost everywhere now.

You all comes about because some people cannot accept the word you as plural.  You can be used when speaking to more than one person.  If you don't understand that, you add the all.  Another example of this based on not accepting you as plural is the ugly word you'ins or the more common yous.

Many waitresses can be heard not trusting you to be plural by addressing two or more customers as you guys.  This may be acceptable English but it is not good English.

Your language is often what people draw from you as a first impression.  Put your best foot forward.  Use good English.
o.o