Football is the most watched sport in all of the world. It is also the most passionately supported.
However, with that passionate love of the game comes a great price. At the worst of times that price is even paid in the form of life.
Football is the one sport that has more violence-related fan injuries or deaths than any other. Unfortunately, that has become an all-too-common occurrence in the game around the world.
Ultra fan groups turn the love of competition embraced in the game into something completely different, and many times violence is the outcome between rival club gangs.
In looking at the effect of violence on the game, we take a look at the 10 most dangerous fan bases around the world.
Poland is a country plagued by football hooliganism and thuggish fans. Wisla Krakow have a major following of raucous and riotous fans whom have caused major problems from one end of the spectrum to the other.
Dino Baggio of Parma FC was allegedly stabbed in the head from a knife thrown by Wisla supporters in 1999, and in 2003 Wisla hooligans were part of a five-club brawl in Wroclaw, Poland.
In the semi-annual "Holy War" rivalry game between Krakow and MKS Cracovia, there is almost a guarantee of casualties or deaths, as fans are always involved in deadly drawls. The 2006 version saw eight people killed in a hooligan battle in the city.
Czech Republic side AC Sparta Prague is the worst in central and eastern Europe. Their hooligan groups communicate through either Facebook or webpages and have some of the most sophisticated followings, as far as organization, in the game.
Ultras Sparta not only will battle with rival fans, but they are not afraid of authority either. The fearless supporters have attacked high ranking members or former members of clubs on multiple occasions.
In 2006 they attacked former Hearts Chairman George Foulkes when Ultras started a brawl with groups of the 5,000 visiting fans from Scotland.
Argentine club River Plate are widely known for their dangerous fans. Riots, fights and altercations are a run-of-the-mill event around the ultra fan groups of the club.
Most club hooligan groups usually fight those of other clubs. However, the fierce River Plate fans sometimes even turn their aggression on themselves, as evidenced in their 2007 gun and knife fight before a match that saw them fighting over where they were to stand in the stadium.
Just this summer one of the club's own fans was stabbed to death during a brawl with fans of Boca Unidos. The young fan, Gonzalo Saucedo, was only 21 years old according to Fox News Latino.
Peruvian club Universitario de Deportes have the most violent fan base in their country, and one of the worst in all of South America.
The radical fans of the club have torched cars and buses of rival fans, but the worst incident included throwing an opposing fan from the stands.
As reported by Edgar Dávila Chota of Infosurhoy in November of last year, 23-year-old Walter Oyarce Domínguez, a student and fan of Universitario opponent Alianza, was thrown from one of the upper levels of the stadium by a fan. He died in the following days from a brain injury after falling more than 50 feet to the concrete below him.
London-based npower Championship club Millwall have been a thorn in the side of English football for decades. The picture of the young fan above is one that could see him eventually grow up to be one of the many fans who give Millwall its frightening reputation.
The Bushwackers are the most famous of their hooligan and thug supporter groups. The group, usually consisting of anywhere from 200-250 at a time, are by far the most fanatical supporters of the club.
AS Roma fans have been involved with numerous altercations with fan violence, stabbings and constant hooliganism and thuggery.
Twice in 2001 Liverpool supporters were stabbed in Rome. Middlesbrough fans were attacked and stabbed in 2006, and in 2007 another altercation with an English side, Manchester United, saw more visiting fans fall victim to thugs.
Local battles with SS Lazio fans have also resulted in violence in Italy's eternal city. The ancient reference that referred to Roman's as the "mob" in ancient times can almost be likened to the fans of modern day Roma, as their emotions are dependent on the win or loss of their club.
Galatasaray fans greeted any opponents walking into the Ali Sami Yen stadium with the slogan of, "Welcome to Hell." The club's old stadium was one of the toughest venues in all of Europe before the club moved to the Turk Telecom Arena in 2011. There, the tradition has continued with double the fan base.
Galatasaray fans have been involved with more thuggish and hooligan activity than many Turkish teams combined. Battles with Fenerbahce, Arsenal and Leeds United are some of the most documented of the club's history.
Not only are the fans some of the most dangerous in all of the game, but according to the Guiness Book of World Records, they are also the loudest.
Colombia is a nation that history has perceived to be dangerous in many ways—and their sporting football culture is exactly that.
Following an unfortunate own goal during the 1994 World Cup, Colombian defender Andres Escobar had his life taken by angered fans in the national capital, Medellin, as reported by Time Magazine on July 11, 1994.
The Port Said riot in February of 2012 was one of the most deadly soccer-related incidents in history. Fans between rival clubs, Al-Masry and Al-Ahly, kicked off what could be labeled as a street war between rival fan bases.
The end result, according to the Huffington Post, saw 74 people die and another 1,500 were believed to have been injured in the bloodshed. The two clubs will never be able to live down the events that followed that fixture for the rest of history.
The 1970 World Cup qualifying round between El Salvador and Honduras, which saw everything from fan suicides to fighting in the streets, eventually led to war.
The three matches between the two countries did nothing but add more fuel to the fire. The event would become known as the Football War and remains one of the more bizarre happenings in footballing history.
You cannot say there are more dangerous fans than ones who will literally go to war with one another over a football match. According to University of Miami research scientist Jay Mallin, nearly 3,000 civilians and soldiers were killed between the two nations, and countless more casualties ensued from the conflict.