Your or You're

So what is it with people, both children and adults, not knowing whether to use "your" or "you're"!!!!! You're is the contraction of "you are". Simply put, just read the sentence, replace it with "you are" -- it either fits or it does not. If "you are" fits, use "you're"!!! I think EVERY facebook page I go to, "your" is used when it should be you're!!!