Note: This is not intended to be a preachy article, but to help those (like me) who want a quick reference sheet for these common mistakes that spell-check frequently misses. (Erm...to that note add I am *not* the best with grammar, myself, so while I hope I caught all errors in the examples, don't count on it and call me on it if I'm wrong!!!)
Its: possessive adjective. Example: The house has shutters on its windows.
It's: contraction for "it is". Example: It's going to be a long day.
Than: used in comparison statements, or preference statements, or to suggest quantities beyond specified amounts. Examples: She is older than I. I would rather eat an apple than an orange. You have to read more than the first paragraph to understand the book.
Then: a time other than now, next in time or order, or suggesting a logical conclusion. Examples: He is busy until noon, but he will join us then. First we study, then we party. If I study hard, then I'll pass that test.
Their: possessive pronoun. Example: The book belongs to them. It is their book.
There: refers to a place. Example: My house is over there.
They're: contraction for "they are". Example: They're going to the mall.
To: preposition, or first part of the infinitive form of a verb. Example: They want to go to the park.
Too: also, very, or to an excessive extent or degree; beyond what is desirable, fitting, or right. Examples: I want to go, too. or She was too sick to travel.
Two: the number.
Your: possessive pronoun. It is in your best interest to know this.
You're: contraction for "you are". You're going to do really well on that test.