Cricket is played in three different formats that are categorised by the length of the matches. A first-class or test cricket match is one which is played across three and five days and features two alternate batting innings for each side. Due to the longer length of a match, scoring rate is slow. There are no limitations on how fielders are placed with respect to the 30-yard circle.
In limited overs or List A cricket, runs are scored at a much faster rate. International cricket played in this format are the One Day International (50-overs per innings) and T20 International (20-overs per innings) matches. The scoring rate is faster in these formats which makes it imperative to have laws that restrict the positioning of fielders across overs.
After several amendments between 2005 and 2015, the rules for field restriction, also called powerplays were finalized to its current shape. The maximum changes were made in the One Day International format.
According to the current rules, an innings features three powerplays – P1, P2, and P3. P1 is a mandatory powerplay between the first ten overs of the innings. During this period no more than two fielders can be placed outside the 30-yard circle.
The second powerplay or P2 can be taken by the batting side any time between the 11th and 40th overs of the innings. It lasts for ten overs and no more than four fielders are allowed outside the inner circle. Finally, the third powerplay is between the 41st and 50th overs. The fielding side can place no more than five fielders outside the 30-yard circle.
The T20 format features one mandatory powerplay which lasts till the sixth over of the innings. Only two fielders can be placed outside the circle. Field restrictions are lifted from the seventh over and no more than five fielders are allowed outside the inner ring.
Various T20 league tournaments have their own rules for the field restrictions. For example the Big Bash, The Hundred, and the Indian Premier League have their own independent rules which are subject to change. Furthermore, the growing popularity of the T10 format which is only selectively sanctioned by the International Cricket Council has its own powerplay rules across leagues.
