League of Legends in esports
League of Legends competition involves professional gamers of the multiplayer online battle arena (MOBA) game, League of Legends, published in 2009 by Riot Games. Professional tournaments began in 2011 with the Season 1 World Championship at DreamHack in Jönköping, Sweden.

Tournaments

League of Legends is one of the largest esports with various annual tournaments taking place worldwide. In terms of esports professional gaming as of June 2016, League of Legends has had $29,203,916 USD in prize money, 4,083 Players, and 1,718 tournaments, compared to Dota 2's $64,397,286 USD of prize money, 1,495 players, and 613 tournaments.

World Championship

The Season 1 Championship was held at DreamHack in Sweden, in June 2011 and had US$100,000 in prizes. The European team Fnatic defeated teams from Europe, the USA, and Southeast Asia to win the tournament and received US$50,000 in prize money. Over 1.6 million viewers watched the streamed broadcast of the event, with a peak of over 210,000 simultaneous viewers in one semi-final match. After Season 1, Riot announced that US$5,000,000 would be paid out over Season 2. Of this amount, $2 million was to go to Riot's partners, including the IPL and other major esports associations. Another $2 million was to go to Riot's Season 2 qualifiers and championship. The final $1 million was to go to small organizers who apply to Riot to host League of Legends tournaments.

After a series of network issues during the Season 2 World Playoffs that led to several matches being delayed, Riot revealed on October 13, 2012, that a special LAN-based client had been quickly developed, designed for use in tournament environments where the effects of lag and other network issues can be detrimental to the proper organization of an event. The LAN client was deployed for the first time during the first quarter-final and semi-final matches played following the rescheduled matches, and was in use during the finals. On October 13, 2012, the Taipei Assassins (TPA) of Taiwan triumphed over Azubu Frost of South Korea in the Finals of Season 2 World Championship with a score of 3 to 1, and claimed the $1 million in prize money.

In October 2013, Korean team SK Telecom T1 and Chinese team Royal Club competed at the Season 3 World Championship at the Staples Center in Los Angeles. SK Telecom T1 won the grand prize of $1 million, and Royal Club received $250,000.

On July 11, 2013, Riot Games announced that the United States Citizenship and Immigration Services recognized League of Legends pro-players as professional athletes and that the P visa application process would be more simplified for them. These changes allowed professional players to stay in the United States for up to five years. Despite these reforms, there have still been a number of visa problems that have occurred for players in the LCS and other LoL tournaments entering the United States.

Silversmith Thomas Lyte was asked to craft the winner trophy for the 2014 games, having already created the Season Two World Championship Cup in 2012. Riot Games, which owns League of Legends, commissioned the Summoner’s Cup and specified that it should weigh 70 pounds. However, the weight was later reduced as it was too heavy to be lifted in victory.

The 2013 tournament had a grand prize of $1 million and attracted 32 million viewers online. The 2014 and 2015 tournaments each gave out one of the largest total prize pools in esports history, at $2.3 million.  The 2016 World Championship's total prize pool was over $5 million, with over $2 million going over to the winner of the tournament.  In October 2015, SK Telecom T1 became the first-ever two-time World Champion when they defeated fellow Korean team KOO Tigers with a score of 3 to 1 in the best-of-five finals in Berlin, Germany.  SK Telecom T1 repeated their feat in October 2016, defeating fellow Korean team Samsung Galaxy 3-2 in the Season 6 World Championship.  The 2016 tournament was also notable for introducing "Fan contributions" to the prize pool; a certain percentage of purchases from Riot's store over the preceding months of the tournament went to increasing the prizes for the 16 competing teams in the tournament.

Mid-Season Invitational 
The Mid-Season Invitational (MSI) is an annual League of Legends tournament hosted by publisher Riot Games since 2015. It is the second most important international League of Legends tournament aside from the World Championship.

Championship Series and various regions' competitions 

On February 7, 2013, Riot Games made the League of Legends Championship Series (LCS) in Europe and North America. This is a league system where ten teams compete to stay in the league. A season consists of two splits, each split separated into a regular season and a playoff. The top three teams from each continent advance to the world championships. Equivalent leagues run independently of Riot also exist some other regions such as the LPL in China and LCK in Korea.