A pronoun is a word which refers to a subject or object which has already been identified. The antecedent is the word which is being referred to by the pronoun. Pronouns are great things, as speech would be unbelievably tedious without them. Pronouns must, however, agree with their antecedents in number and gender, and many people are not careful enough about this. Many people make the foregoing mistake because they do not wish to use a gender-specific pronoun.
Apostrophes indicate possession and form contractions.
Apparently, the use of apostrophes is extremely confusing to many people. If you use apostrophes in this manner you must stop doing so immediately. That's all there is to say about indicating possession with apostrophes. Use apostrophes to form contractions Apostrophes are also used to form contractions. We are told that contractions were invented by sign-painters back in the olden days because they kept running out of room or paint when they were plying their trade.