My pet peeve is people writing 'defiantly' instead of 'definitely'. It has a completely different meaning and worse, it still makes sense so one has no idea of what the person wants to say. One thing I've always wondered is what happens when such person needs to use the word 'defiantly' in its correct definition? Do they write it the same way?
As for me, English is not my first language so I do make many mistakes but they tend to be mistakes native speakers would never do. My most common one is experiencing vs experimenting. It can be very confusing too. I'm trying to think before using these two words but sometimes I still make the mistake.
