The possessive form of a noun is typically created by adding an apostrophe and the letter S, as in wit’s end. It would be reasonable to expect that possessive pronouns would follow suit, but they don’t. Possessive pronouns – including its, mine, yours, hers, his, ours, theirs – do not contain apostrophes. The word it’s is a contraction of it is, and the apostrophe stands for the missing character.