Sit-ins were a powerful form of nonviolent protest used during the Civil Rights Movement in the United States, particularly in the 1960s. Sit-ins involved African American activists sitting down at segregated lunch counters, restaurants, or other public facilities that were designated "whites only," and refusing to leave until they were served or until the establishment closed.

One of the most famous sit-ins took place in February 1960 at a Woolworth's lunch counter in Greensboro, North Carolina, where four African American college students staged a sit-in to protest the store's policy of serving white customers only. The sit-in sparked a wave of similar protests across the country, leading to the desegregation of many public establishments.

Sit-ins were a key tactic in the broader strategy of nonviolent resistance employed by the Civil Rights Movement, and they helped to bring national attention to the injustice of segregation and discrimination. The bravery and determination of the activists who participated in sit-ins played a significant role in advancing the cause of civil rights and ultimately led to the desegregation of public spaces.