Rosa Parks's decision to refuse a bus seat to a white passenger became the catalyst for the Montgomery Bus Boycott, fundamentally altering the course of the American Civil Rights Movement. Parks's act of defiance on December 1, 1955, symbolized resistance against racial segregation and injustice. Her arrest sparked a year-long boycott led by Martin Luther King Jr., demonstrating the power of peaceful protest. This pivotal action galvanized support for civil rights, highlighting the importance of individual agency in the struggle for equality. Parks's contributions exemplify how one person's bravery can inspire societal change and mobilize communities for justice.