True cinnamon is Ceylon cinnamon, Cinnamomum verum. Here is how it differs from Cassia, what a US label does and does not tell you, and how to check at home.

US federal law doesn't require a cinnamon label to say whether it's true Ceylon cinnamon or cassia — legally, "cinnamon" covers both. Here's the actual regulation, what a 2024 industry investigation found, and how to check what's really in your jar.