It’s the most common error in English, and Spellcheck doesn’t catch it (although Spellcheck catches me when I attempt to spell Spellcheck “Spellcheck,” much preferring two words or a hyphenation to my single word). This prompts me to recycle this post of mine (ever-so-slightly edited):
I try my best to pay attention to grammar and spelling, helped out by the always-handy Spellcheck (shh—don’t tell anyone, but I’m not the world’s best speller, unaided).
But Spellcheck has its limits. And one of them is the proper use of the word “its.” “Its,” that is, vs. “it’s.”
Have you ever noticed how often those two words are confused? Even though I try to pay close attention, I’m always catching myself messing up, and my bet is that, despite my best efforts, some of them have slipped by here. I see it all the time in the work of others, too (and no, I’m not going to do an exhaustive search and link to examples; you’ll just have to take my word for it. Or not.)
The error almost always goes in one direction only: the use of the apostrophe, as in “it’s,” for the possessive form of the word, when it should only be used for the contraction “it is.” Example (the one that sparked this rumination): originally, instead of “…see this from Reuters, not known for its right-wing bias” I had written “…see this from Reuters, not known for it’s right-wing bias.”
Why do we do this? Are we all just stupid! No, no, a thousand times no! We are actually very smart, because we are extrapolating a general rule to include this word, and that is the rule about forming possessives. Usually we do this by adding an apostrophe and an “s,” as you no doubt well know. But with the words “it’s” and “its,” we choose to reserve the apostrophe for the contraction, and that leaves the possessive hanging out there, alone and forlorn and apostropheless.
In this, however, we’re following another rule (are you still with me? or have I already bored you to tears?), that of the possessive personal pronoun: hers, his, theirs, ours, yours, for example. All lack apostrophes. But they’re not confusing, somehow—perhaps because, unlike “its,” they clearly refer to people, and are never given an apostrophe because they never become contractions.
Now, aren’t you glad I cleared that up? But I bet it won’t stop me from making the same mistake again—and again and again.