A more thorough explanation:

The American Civil Liberties Union (ACLU) is an organization founded in 1920, with the mission of defending and preserving the individual rights and liberties guaranteed to all people in the U.S. Constitution.

The ACLU currently has more than 1.7 million members, 500 staff attorneys, thousands of volunteer attorneys, and several offices throughout the United States.

Within its organizational mission, the ACLU engages in activities such as:

• Fighting for racial justice
• Maintaining freedom of and from religion
• Preserving freedom of speech
• Defending liberty in times of national crisis
• Applying the Bill of Rights to criminal justice
• Protecting women’s equality
• Safeguarding reproductive freedom
• Fighting for equality of the LGBT community
• Guaranteeing the right to vote

For example, the ACLU may file a lawsuit against a state government that is trying to pass a law that would restrict access to abortion. This would fall under their mission to safeguard reproductive freedom.

Another example would be the ACLU defending the right of a student to wear a t-shirt with a political message to school. This would fall under their mission to preserve freedom of speech.

Overall, the ACLU works to protect the rights and liberties of all individuals, regardless of their background or beliefs.