Part of what I do for a living is write. I’ve co-authored a book, written a rather large number of technical articles, and I’ve also done professional editing, tech review, and manuscript review for magazines, newspapers, and publishing houses. Also, my wife is an English teacher. In short, though I make my fair share of mistakes, I have some clue what I’m talking about with regards to grammar. So, here are what I think are by far the most common mistakes I see people make, both in formal (articles and such) and informal (IRC and such) writing:
- there, their, and they’re - “there” is a place. “their” is possessive. “they’re”, as implied by the fact that it’s a contraction, is two words: “they are”.
- its and it’s – Never use “it’s” unless you want to say “it is”. Any other time, use “its”. At no time should you be thinking that “it’s” is somehow possessive. Some people think “it’s” can also mean “it has”. You’re free to make your own call on that. I would personally avoid that usage – and I do, regularly. The goal of language *usage* is not to raise eyebrows. The goal should be to use language to communicate ideas, and the *ideas* should raise the eyebrows.
- your and you’re – again, only use “you’re” when you mean “you are”. Period, end of story.
- kernel and kernal – kernal is just not a word. It’s kernel, not kernal. Kernal is never right.
- too and to – “too” should only be used in a place where “as well” would also fit. I would generally chalk this up to typos, but I’ve just seen it misused too consistently. Nobody misses that last “o” *every* time!
- ‘s - There are lots of places where this is useful, but it should never be used to make something a plural. To make something a plural, you either add an “s” or an “es” – but you never add ‘s to make something plural to my knowledge. It’s used in contractions, and possessives. Not plurals.
So really, that’s it – oh! By the way – “thats” is not a word. That’s always written “that’s”. I can’t think of an instance where “thats” is useful, but I’m not all-knowing either. It would be awkward, at best.
Anyway, there really aren’t a whole lot of them, but if everyone on the internet just paid attention to *just* those things – it would be a vast improvement.