Rosa Parks’s defiance, by refusing to relinquish her bus seat, was a pivotal act in the civil rights movement. Her arrest sparked the Montgomery Bus Boycott, a significant protest against racial segregation that lasted over a year. This pivotal event galvanized support for the movement, leading to increased activism and the rise of influential leaders, including Martin Luther King Jr.. Parks's action exemplified courage and resistance, inspiring others to challenge injustice. The boycott also led to a Supreme Court ruling that deemed segregation on public buses unconstitutional, marking a significant victory for civil rights.