The correct use of the apostrophe is often misjudged. This video explains a couple of ways to get the placement of an apostrophe correct.
There are some circumstances where apostrophe placement changes subtly. Such as, not putting another 's' after a possessive apostrophe, when the word already ends in an 's'. Also, what about those quote marks used in that last sentence?
For early learning, stick with the simple rules shown in the video to avoid confusion. For further learning, follow the links below.