One confusing pair of words to write out is its and it’s.
is a possessive form of it, meaning belonging to it.
is a contraction of the words it is or it has.
To figure out which is correct for your sentence, just swap in “it is” and then “it has“. If the sentence makes sense with either of those substitutions, use it’s. If the resulting sentence doesn’t make sense, you need its!
It’s is a contraction of the words it and is or it and has. The contraction keeps the sentence short, simple, and easy to read. It also makes it sound more like natural, real-life speech. In the sentence “It’s unclear what he meant,” it’s can be swapped with it is: “It is unclear what he meant.” Perfect.
Let’s look at an example of when it’s is a contraction for it has, as in “It’s got to be finished today.” In this case, it’s got is a contracted form of it has got. In more formal speech, you would use it has. Keep in mind that even in informal writing, you should use helping verb (like been or got) when it’s is short for it has.
Its indicates possession, and appears in front of the noun it describes. If you hear “The hotel raised its rates,” you know that the rates belong to the hotel.
This can be triply confusing because most words use an apostrophe to indicate possession (e.g. “Mary‘s bike”). But not all possessive pronouns follow this pattern. For example, your, his, her—and its—just don’t.
And never its’
Another rule to keep in mind: the combination its’ is always wrong. The apostrophe never follows the s. It’s nice to be able to say “never” for an English grammar rule…it doesn’t happen very often.