It's or its? To determine if you should use it's, replace the sentence that has it's with it has or it is. If it works, it's is correct. It's is a contraction and is a short form for saying it is or it has. Examples are: It's raining out. It's been fun hanging out with you. It's almost dinner time. For each of those statements the it's can be replaced with it is or it has. However, look at these statements: Madrid is known for its paintings. The dog hurt its tail. It is doesn't work. Therefore you don't need the apostrophe in its.