In 1963, more than 200,000 people came to Washington, America's capital, to hear one man speak. His name was Dr. Martin Luther King.
And the words he said that day are some of the most famous in history.
He said he had a dream that life for his children could be different from how it had been for him. But what did he mean?
Dr. King lived in a part of America that had racist laws that treated black people unfairly.
Racists believe people with certain skin colours, or who are from a particular race, are better than others so they treat them differently. So black and white people were kept apart, eating in different restaurants, travelling in different parts of buses and it was hard for black people to vote against the people who made these laws.
He had many enemies and was sent to prison.
After his release, he went to Washington.
There, in front of a huge crowd and with many more people tuned to their TV and Radio, he told of his dream that his children would one day live in a nation where they wouldn't be judged by the colour of their skin but by the content of their character.
People everywhere, began to share Dr. King's dream and knew that the racist laws had to change. Not everyone agreed though.
In 1968, Dr. King was shot dead for his beliefs.
But the changes he started continued after he died and so he's remembered. Every year Americans celebrate his life with a public holiday called Martin Luther King Day. Remembering a strong man and brilliant speaker.