Question 1

When do I use "it's" with an apostrophe?

Accepted Answer

Only when you mean "it is" or "it has." Everywhere else, the possessive its has no apostrophe. It's raining unpacks to it is raining. It's been a while unpacks to it has been a while. If the unpacking breaks the sentence ("the dog wagged it is tail"), you want the possessive its. The apostrophe in it's stands in for a missing letter — the i of is or the ha of has. That's the same logic as don't (do not) or she'll (she will). Once you read the apostrophe as a "something is missing here" sign, the rule becomes obvious. Exception: None. If you can replace the word with it is or it has, the apostrophe is correct. If you cannot, the apostrophe is wrong.

Question 2

Is "its" or "it's" the possessive?

Accepted Answer

Its (no apostrophe) is the possessive. It's (with apostrophe) is short for "it is."

Question 3

Is it "its a dog" or "it's a dog"?

Accepted Answer

"It's a dog." The phrase is a contraction of "it is" — the apostrophe belongs.