My is a possessive adjective that shows ownership or relationship. When you say “my book,” you're indicating that the book belongs to you. When you talk about “my sister,” you're showing your relationship to her.

We use my constantly in everyday speech. “That's my desk.” “I forgot my homework.” “My dog loves to play fetch.” The word creates a connection between you and whatever follows it, whether that's a physical object, a person, an idea, or even an experience. You might say “my opinion” or “my mistake” to show that the thought or error belongs to you.

My is one of the first words children learn because it expresses something fundamental: the relationship between ourselves and the world around us. It's closely related to other possessive words like mine (which stands alone, as in “that book is mine”), your, his, her, our, and their.

Notice that my doesn't just show legal ownership. When you say “my country” or “my school,” you're expressing a sense of belonging and connection, not claiming you literally own these things. The word helps us talk about everything we're connected to, from “my birthday” to “my responsibilities” to “my dreams for the future.”