Big Bash League
The BBL was introduced by Cricket Australia in 2011 to replace the Twenty20 Big Bash, which was a tournament between six state-based teams. The BBL is played by eight city-based franchises. Each team plays the other at least once in the league stage; until now, each team played every other team twice. This will change in the 2017-18 edition, when each team will play two more games. Teams are allowed two overseas players in their squad, and the tournament usually attracts top players from West Indies and England.
Pakistan Super League
The PSL is two seasons old and is run by the Pakistan Cricket Board. It has so far featured five teams, but a sixth will be added for the third edition. One of the objectives of the league is to bring top-level cricket back to Pakistan, and the final of the 2017 tournament was held in Lahore. Teams are allowed to have eight foreign players in their squads and to field four in their XI. So far, PSL teams have managed to buy top players from the West Indies, England, New Zealand, South Africa and Sri Lanka.
Indian Premier League
The biggest T20 league in terms of viewership, the IPL has already completed ten seasons and has seen several format changes over the years. Just five of the original eight teams have played every season, and several franchises have had short lives. Gujarat Lions and Pune Supergiant played the last two seasons, but will not be around for the 2018 version, when Rajasthan Royals and Chennai Super Kings will return from suspension. Players from every Test-playing country have been a part of the IPL, which allows four overseas players in a side's playing XI.
NatWest T20 Blast
The ECB has tinkered with its domestic T20 tournament several times since it first hosted one, in 2003. The latest version, the NatWest T20 Blast, has the 18 county sides divided into two groups. Each team plays six of the teams in their group twice and the other two once. The top four teams in each group enter the knockouts. Each team is allowed to field two international players in their XI. The ECB plans to launch a new city-based T20 tournament in 2020.
Caribbean Premier League
The CPL is privately owned but fully sanctioned by Cricket West Indies. It has six teams who play a double round-robin stage from which four reach the knockouts. The Antigua Hawksbills franchise was replaced in 2015 by the St Kitts and Nevis Patriots.
Bangladesh Premier League
The BPL was launched by the Bangladesh Cricket board in 2012, with seven city-based franchises competing against each other. The first edition was held in February and a second was played a year later. Accusations of match-fixing led to the tournament being suspended for two years, before it returned in 2015-16 with a new set of franchises. While six teams participated in the 2015-16 season, seven were part of the most recent one, with two new franchises being added and the Sylhet franchise being suspended. Sylhet will return for the 2017-18 season, with new owners.