When do you use an apostrophe "s"?

You use an apostrophe S when showing possession. Example, "Claire's ball."
You can also use it when a word ends in an S to make the sentence flow better. "Thomas' ball." Similar to how you use "an" instead of "a" before vowels to make it flow better.
Also watch out for "its" and it's". Usually apostrophe S means possession, but in this case "its" without the apostophe shows possession, while "it's" with apostrophe is a contraction for "it is"
====================================================
Running Shoes|Fitflops