To be selfish means to care primarily about yourself and your own needs while ignoring or dismissing what others need or want. A selfish person takes the last slice of pizza without asking if anyone else wants it, hogs the playground equipment, or refuses to share supplies even when a classmate is struggling.

Selfishness shows up in small moments and big ones. The selfish teammate won't pass the ball because they want all the glory. The selfish friend always picks the movie or game they want to play, never considering what others might enjoy. When someone acts selfishly, they're basically saying, “What I want matters more than what you want.”

Everyone acts selfishly sometimes. You might grab the best seat without thinking, or forget to save your sister a cookie. That's being thoughtless or inconsiderate. But truly selfish people make it a pattern: they consistently put themselves first and rarely think about how their choices affect others.

The opposite of selfish is generous or considerate. Between these extremes lies healthy self-care: taking care of your own needs while also respecting everyone else's. Learning when to think of others and when to stand up for yourself is one of the trickier parts of growing up. The key difference is whether you're willing to think about other people's needs too, or only your own.