What means: Visitor Log -> Referrer URL - campaign?

At the visitor real time log i got some entrys:

Referrer URL --> campaign / Twitterfeed

What does that mean???

Thank U


Someone clicked on a link to your website, that was published on Twitter by a person using Twitterfeed.com, a service that tweets blog posts automatically, and add the Campaign tracking parameters automatically (GA format, detected by Piwik)

Thank You