Do remember that your IELTS examiners check for punctuation errors in your written work, so learn more about this punctuation mark in The Oatmeal - How to Use an Apostrophe.
Cheers!
Other comics relating to grammar and punctuation from The Oatmeal:
What it means when you say "literally"
When to use "i.e." in a sentence
How to Use an Apostrophe
Ten Words You Need to Stop Misspelling
