Learn when it's appropriate to use its vs. it's with Grammar Rules from the Writer's Digest editors, including a few examples of correct and incorrect usages.
Okay, full disclosure: I made the it's vs. its mistake at the very end of my most recent grammar post on a lot vs. alot vs. allot.
But it's just so easy to mistake these two, even when you know the rules. So, let's take a look at the rules and make sure we agree on those first.
Its vs. It's
Its is often referred to as either an adjective or possessive pronoun. Either way, its is the possessive form of the pronoun it. Say you have a computer and want to refer to the computer's keyboard, but you want to replace the word "computer's" with a pronoun. Well, you'd replace "computer's mouse" with "its mouse." Coincidentally, "its mouse" could also refer to a cat that has captured a small rodent, which is why some grammarians are so opposed to the word "it," because "it" can mean many things.
It's, on the other hand, is a contraction of the two words it and is. A common thing people may say is that, "It's nice outside," which means "It is nice outside." Or if that cat is chasing mice again, someone may exclaim, "That cat! It's chasing mice again!"
If not, here are a couple examples:
Correct: I like writing with this pencil, but its eraser is annoying. It's always leaving pink smears on the page.
Incorrect: I like writing with this pencil, but it's eraser is annoying. Its always leaving pink smears on the page.
Correct: It's fun to own a cat, because its company is comforting.
Incorrect: Its fun to own a cat, because it's company is comforting.
Believe it or not, the same reason grammarians eschew the word "it" is the same reason so many non-grammarians love it. It's incredibly flexible and can take on a variety of meanings depending upon its purpose.