Anybody can make a difference, and it can be as simple as saying, "No."

In 1955, Rosa Parks was riding a bus in Montgomery, Alabama. The normal practice on buses was to make African Americans sit in the back, while white people got to sit in the front. Sometimes bus drivers would even drive off before African Americans had a chance to board.

Basically, take the frustration of missing a bus, add about a ton and half of racially-motivated persecution and injustice, and you're almost halfway to how jacked up this was.

One day, Rosa Parks was riding the bus and refused to give up her seat to a white woman. This was an unorganized, spontaneous example of a "sit-in," a type of protest where African Americans would just go sit where they weren't "supposed" to sit (for example, segregated restaurants).

Rosa Parks' action was an initial step in the bus boycott, led by Martin Luther King, Jr. African Americans stopped riding buses in Montgomery to protest the injustices of the day.