A more thorough explanation:

Definition: A sit-in is a type of peaceful protest where people sit or lie down in a public place and refuse to leave as a way of showing their disagreement with a policy or activity.

Sit-ins started as a way for people who were discriminated against because of their race to protest against segregation. They would sit in places where they were not allowed to be and refuse to leave. Later on, the term was used for any group protest, like anti-Vietnam War protests and some labor strikes.

Example: In 1960, four black college students sat down at a "whites-only" lunch counter in Greensboro, North Carolina. They refused to leave until they were served, and their peaceful protest sparked a wave of sit-ins across the country.

Example: In 2018, students at a high school in Florida organized a sit-in to demand stricter gun control laws after a mass shooting at a nearby school. They sat in the school's courtyard for 17 minutes, one minute for each victim of the shooting.

These examples show how sit-ins can be used to peacefully protest against policies or activities that people disagree with. They are a way for people to make their voices heard without using violence or aggression.