Exclusion means leaving someone or something out, either on purpose or by accident. When a group of friends plans a party but doesn't invite one classmate, that's exclusion. When a club has rules that prevent certain people from joining, that's also exclusion.

Being excluded feels like standing outside a door that's closed to you. Sometimes exclusion happens without anyone meaning harm: if your soccer team practices after school but one player has to leave early for music lessons, they're excluded from practice because of circumstances.

Other times, exclusion is deliberate and hurtful. History shows many painful examples: laws that excluded people from voting, rules that kept certain children out of good schools, or policies that prevented people from living in particular neighborhoods.

The opposite of exclusion is inclusion, which means making sure everyone who should be part of something gets to participate.