Most nouns use an apostrophe s (‘s) to make the possessive (for example, Bill Belichick’s questionable coaching style, the quarterback’s excuses, the team’s dedication); pronouns, however, do not. The most common of these types of errors is the spelling of its/it’s.

It’s means it is, as in It’s time to correct one of the most common errors in the English language and The problem is that it’s easy to confuse the two spellings.

Its is the possessive form of it, as in The English language has its share of problems or Its problems are sometimes self-evident, but we make the mistakes anyway.

I know that it seems as if it should be the opposite—it’s should be the possessive since that’s the way nouns make the possessive. Just use reverse logic on this one. Its (the possessive) is like other pronouns: ours, theirs, hers, his, yours. We don’t use ‘s for those, and we don’t use ‘s for its.

Sherry

Sherry’s Grammar List and Paul’s book–Literally, the Best Language Book Ever