Selfishness means caring only about what you want, without thinking about how your actions affect others. A selfish person takes the last cookie without asking if anyone else wants it, hogs the playground equipment, or refuses to share supplies even when a classmate really needs them.

Selfishness means putting yourself first in ways that hurt or ignore other people. Everyone needs to take care of their own needs sometimes: that's sensible self-care. But selfishness crosses a line. When your sister is selfish with her birthday cake, she might refuse to give anyone else a slice. When a teammate plays selfishly in soccer, they never pass the ball, even when someone else has a better shot.

The opposite of selfishness is generosity or thoughtfulness. Most people aren't completely selfish or completely selfless: we all struggle sometimes with the balance between our own wants and others' needs. But persistent selfishness can make people lonely, because others eventually avoid someone who only thinks about themselves. True friendships, strong teams, and happy families depend on people caring about each other, not just themselves.