I've given up on it's versus its.

His, hers, theirs, ours, its. None of 'em has an apostrophe.

Why is that so difficult to learn? It's not all that damned arcane.

And...it is, when shortened, becomes it's.

If you're not sure if *its* is correct (no apostrophe), try substituting his, hers or ours. English is modular; if one works, the other is correct also.

But as I said, I give up. I've spent more than 30 years trying to help people tell when to use which, and I've come to the conclusion that it's a lost cause. Teachers spent so many years drumming it into youthful heads that the apostrophe is the writer's best friend that *it's* is the only form people seem to be able to use.

Sometime's you jus't need to k'now when it's a los't cause.