Writing can be hard. There are so many tricks and inconsistencies that it’s hard to keep track of which rules to use when.

For this week’s Weekly Rewind, we’ve rounded up the most common mistakes made while writing.

The Stuff Your Spellchecker Won’t Catch

Everyone should know the difference between it’s and its, their, there and they’re and to, too and two. If you need a refresher, please pause and read Skills You Need for a review.

For the grammar errors your spellchecker won’t catch, PR Daily has a list of the more complicated mistakes, such as alright and all right, i.e. and e.g. and lead and led.

You Might Be Using Indefinite Articles Wrong

When we were tots we were taught that ‘a’ goes before consonants and ‘an’ goes before vowels— not so! As PR Daily explains, ‘an’ goes before vowel sounds and ‘a’ goes before consonant sounds, regardless of how the word is spelled. Confusing? Here are some examples:

• a hotel
• an heir
• a unicorn
• an umbrella

Never Leave Home Without Your AP Stylebook

In PR we eat, sleep and breathe AP Style. However, if you’re caught without your trusty AP Stylebook, Ragan has some basics you should know, including farther versus further and correct state abbreviations.