Today's Croke Park Classic will see University of Central Florida host Penn State in their 2014 Season Opener. The event has brought an estimated 20,000 American visitors to Dublin.

Are you intending to follow the game today but a little bit rusty on your American football rules? Check out our infographic below. It offers you a quick crash course that should set you up on the basics before today's game.

Click to enlarge the picture below, and also check out our guide on the players to watch today.

Click to enlarge