First source

The earliest publication of a claim that can be found, the origin the copies trace back to.

The first source of a claim is the earliest place it was published, by the person or organization that actually made it. Later articles, posts, and summaries that repeat it are copies, even when they are far more visible than the original.

Finding the first source matters for two reasons. It shows whether the claim was stated accurately in the first place, because claims often change as they are repeated. And it tells you where a correction will do the most good: when the original is corrected, the copies lose the original they cite.

See how to find where a claim started.