The Super Bowl, at its most basic level, is a game that determines the NFL championship.
It has become so much more since the first game was played in 1967.
Super Bowl Sunday has become an unofficial holiday in the United States. It's a day when families and friends gather to watch the game, the over-the-top commercials and big-name musical acts at halftime.
The game and the two weeks of hype, parties and other events leading up to it have turned the Super Bowl into a spectacle. It ranks up there with the Olympics or World Cup, a royal wedding or papal celebration, the Oscars or Grammys.
This year's game, between the Seattle Seahawks and New England Patriots, is scheduled Sunday. Here's some reasons why the Super Bowl is so special.
Baseball is known as America's pastime. But football is woven into the country's fabric.
The NFL's rise came at the same time as television's and turned into a $9 billion enterprise. The NFL season has far fewer games than the other major North American sports, 16 compared to 162 in baseball. That makes every NFL game an event.
Once the season gets to the Super Bowl, many of the fans don't get a chance to go. Tickets started around $800 for this year's game. Most are snapped up by corporations.
Cities bid for the right to host the Super Bowl. Many use the game as a rallying point to build a new stadium and bring in revenue.
The game is rotated every year, usually to a warm-weather city or one with a domed stadium.
Last year's game was played in the stadium the New York Jets and Giants share in East Rutherford, New Jersey. It was the first outdoor game in a cold-weather city. Future games will be in San Francisco, Houston and Minneapolis.
Arizona's University of Phoenix Stadium, site of this year's games, has a retractable roof and a field that is wheeled outside so the grass can get sunlight.
The Super Bowl is one of the most-watched events in the world. It routinely draws more than 80 million viewers. The game has eclipsed 100 million viewers each of the past five years. A record 111.5 million watched Seattle roll over Denver a year ago.
Millions more watch the game around the world.
Super Bowl commercials have become a part of the show. They lure viewers who might not otherwise watch the game.
Over the years, the commercials have included talking animals and babies, supermodels and Clydesdales, sophomoric humor and tear-jerking moments.
The rate for this year's game is $4.5 million for a 30-second spot.
This year's halftime show will feature Katie Perry and rock guitarist Lenny Kravitz. Other halftime Super Bowl performers have included Bruce Springsteen, The Who, Prince, Madonna and Bruno Mars with the Red Hot Chili Peppers last year.
Critical thinking challenge: Why are companies willing to spend so much money for Super Bowl ads?