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.