This morning, Facebook begins its defense of its Timeline product against a website who claims that its continued use amounts to trademark infringement.

The website, Timelines.com, lets users create and edit “timelines” of historical events. They sued Facebook back in October of 2011, just weeks after Facebook announced their new Timeline product at the company’s f8 conference. As of now, all Facebook users have the new Timeline, which is an update of the traditional Facebook profile page.

Timelines.com claimed that Facebook was infringing upon their trademarks by operating the new profile under the name “Timeline.” Facebook quickly countersued, claiming that the term “timeline” is generic – too generic in fact to deserve any sort of federal trademark protections. They have argued that the trademarks should be canceled.

“Given the generic or at least merely descriptive nature of the term ‘timeline’ when used to identify chronologies of events and related information (or tools for their creation), as well as the prior and widespread use of the term by third parties, Counterdefendant does not own exclusive rights in the term ‘timelines’ as used in connection with timeline creation and collection services,” says Facebook.

Earlier this year, Facebook asked U.S. District Judge John W. Darrah to dismiss the original suit. And a few weeks ago, Darrah ruled that the claim must go to trial. He said that Facebook had ““failed to demonstrate, as a matter of law, that the marks are generic.”

He also concluded that with “millions of dollars invested in its business and more than a thousand active users,” it’s reasonable to believe that the word “timeline” has its own specific meaning to Timelines.com users.

Timelines.com has just shy of 100,000 visitors a month, while Facebook boats over 1 billion monthly active users. The trial began this morning in the Northern District Court of Illinois.