To start let me say that the meaning of all of these sentences is the same. They are all telling you who the thing belongs to, the only difference is what you are emphasizing. When you use "my" it puts greater emphasis on the object. When you use mine it puts greater emphasis on who the object belongs to. How to use them correctly is defined below: Mine is a pronoun whereas my is an adjective; to be more specific, mine is a possessive pronoun, whereas my is a possessive adjective. So the word mine is used in reference to a noun, and my is used to describe a noun. For example: This is my house. My is describing the house, who it belongs to. The object after the word "my" is what matters. You are simply clarifying to someone that it is yours. This house is mine. Mine is referencing the house, also who it belongs to. The object is not as important here, but whose it is matters greatly. You are telling someone with emphasis that the house belongs to you. Side note (This may or may not be helpful) The part that is confusing about this is that the other possessive pronouns and possessive adjectives used in English are the same for other subjects. If I'm talking about you instead of me the examples would be: This is your house This house is yours. or This is his house. This house is his. or This is their house. This house is theirs. or This is our house. This house is ours.