Resentment is a bitter, angry feeling that builds up when you believe someone has treated you unfairly and you can't stop thinking about it. Unlike simple anger that flares up and fades, resentment sticks around, growing stronger over time like a splinter that works its way deeper under your skin.

Imagine your teacher always calls on the same student to help with special projects, never giving you a chance. At first you might feel disappointed, but if it keeps happening, that disappointment can turn into resentment. You start noticing every time it happens, feeling more and more bitter about the unfairness. Or perhaps your older sibling constantly gets privileges you don't, and every time you think about it, you feel that familiar angry knot in your stomach.

Resentment often comes from feeling powerless to change a situation. A teammate who sits on the bench game after game might resent the coach. Someone who works hard while others slack off might harbor resentment toward those who get credit they didn't earn.

The tricky thing about resentment is that it usually hurts the person feeling it more than anyone else. While you're stewing over what happened, the other person might not even know you're upset. Resentment can poison friendships, make you unhappy, and keep you stuck in the past instead of moving forward.