Rugby, also known as Rugby League, is one of the two major codes for rugby football; the other being Rugby Union. The sport is highly physical and is touted to be one of the most celebrated sports in UK. It is also often cited as one of the world’s toughest and most physically demanding sports. As with most sports, the game is played on a field, with two teams having thirteen players each playing for possession of the ball. The ball being used in this game bearsa number of similarities with the American football. It has the same basic shape as a football although the ends are more rounded to allow for a good bounce when players attempt drop goals. Most rugby balls are made of synthetic materials and usually have no visible laces, unlike the American football. The primary objective in rugby league games is to carry or kick the ball towards the opponent's goal line, where points can be scored by grounding the ball. In rugby, this is known as a try. A team is allowed to try for a goal with a conversion, or a kick for further points. The opposing team will then attempt to prevent the attacking side from gaining points by impeding their progress up the field. This is usually done by tackling the player who is carrying the ball. Rugby league games are played at semi-professional and amateur levels in the United States, as well as in some countries, such as Germany and Japan. The sport enjoys prominence in Australia, England and New Zealand; each country having a popular rugby league club that gains a major following. Rugby league also happens to be the national sport in Papua New Guinea. Worldwide, there are two fully professional leagues recognized in rugby league. The first is the European Super League, which has fourteen member clubs. Twelve clubs are from England, and one rugby league club each from Wales and France. The second professional rugby league is organized in Australia. It is known as the National Rugby League, and it consists of fifteen member clubs. One rugby league club hails from New Zealand, while the remaining fourteen member clubs are from Australia.