After 200-plus years, the U.S. Constitution still defines and limits the powers of American government and guarantees the rights of the American people. How can it, or any nation’s constitution, remain effective in a world that changes every day? How can words drafted by men who traveled to the Constitutional Convention in horse-drawn carriages and (some of whom) owned slaves remain relevant today?

For many, the answer is that a constitution is a “living document.” The words don’t change, unless specifically amended, but the way judges, lawmakers and citizens interpret them does. And now the National Constitution Center lets you watch as the Constitution evolves, changes over time and adapts to new circumstances.

Check out the Interactive Constitution. It pairs the document text with easily understood (promise!) explanations from leading scholars. Sometimes the scholars disagree. That happens with living documents.

Today more than 160 countries have written constitutions. (Others have unwritten ones, where customs, usage and legal precedent serve the same functions.) Google has a great English and Arabic language tool that lets you compare constitutions on key issues like women’s rightsfree speechreligion and election laws.

At the U.S. Constitution’s bicentennial in 1987, Supreme Court Justice Thurgood Marshall warned against letting the occasion become “little more than a blind pilgrimage to the shrine of the original document now stored in a vault in the National Archives.”

Does your constitution reflect the role you think government should play in your life? What are you most proud of, and what would you want to see changed?