Racism is when people treat other people badly because of the color of their skin. In the United States, some people with lighter skin (often called 'white people' or people of European descent) have treated people with darker skin (often called 'Black people' or people of African descent) very badly. This has happened for hundreds of years and still happens today even though it is wrong. It can take lots of different forms, like people using racial slurs, or treating people differently because of their race or ethnicity, or excluding them from certain places or activities. It can also be more subtle and hard to notice. No matter what form it takes it is always wrong and needs to be stopped.