In the main the Laws of cricket apply. However, in ODIs, each team gets to bat only a fixed number of overs. In the early days of ODI cricket, the number of overs was generally 60 overs per side but now it has been uniformly fixed at 50 overs.
Simply stated the game works as follows:
An ODI is contested by 2 teams of 11 players each.
The Captain of the side winning the toss chooses to either bat or bowl (field) first.
The team batting first sets the target score in a single innings. The innings lasts until the batting side is "all out" (i.e., 10 of the 11 batting players are "out") or all of the first side's allotted overs are used up.
Each bowler is restricted to bowling a maximum of 10 overs (fewer in the case of rain-reduced matches and in any event generally no more than one fifth or 20% of the total overs per innings).
The team batting second tries to score more than the target score in order to win the match. Similarly, the side bowling second tries to bowl out the second team for less than the target score in order to win.
If the number of runs scored by both teams are equal when the second team loses all of its wickets or exhausts all its overs, then the game is declared as a 'tie' (regardless of the number of wickets lost by either team).
Where a number of overs are lost, for example, due to inclement weather conditions, then the number of overs may be reduced. Where the number of overs available for the team batting second is perforce different from the number of overs faced by the team that batted first, the result may be determined by the Duckworth-Lewis-method.
The essence of the D/L method is 'resources'. Each team is taken to have two 'resources' to use to make as many runs as possible: the number of overs they have to receive; and the number of wickets they have in hand. At any point in any innings, a team's ability to score more runs depends on the combination of these two resources. Looking at historical scores, there is a very close correspondence between the availability of these resources and a team's final score, a correspondence which D/L exploits.
Using a published table which gives the percentage of these combined resources remaining for any number of overs (or, more accurately, balls) left and wickets lost, the target score can be adjusted up or down to reflect the loss of resources to one or both teams when a match is shortened one or more times. This percentage is then used to calculate a target (sometimes called a 'par score') that is usually a fractional number of runs. If the second team passes the target then the second team is taken to have won the match; if the match ends when the second team has exactly met (but not passed) the target (rounded down to the next integer) then the match is taken to be a tie.
The floodlights would be positioned in such a way that it would not interfere with fielding teams and captains would be allowed a cloth on field should the ball become moist.
The bowling team is subject to fielding restrictions stipulating that nine fielders, including two fielders in catching positions, must be inside the fielding circle for a set number of overs. Traditionally, the fielding restrictions applied for the first 15 overs of each innings.
In a 10 month trial period starting 30 July 2005, the ICC introduced the Powerplays rule as part of a series of new ODI regulations. Under the Powerplays rule, fielding restrictions apply for the first 10 overs, plus two blocks of five overs (called Powerplay Fives). From October 2008 the batting side decides when one of the remaining two blocks occur, the fielding side decides when to begin the other Powerplay. In the first Powerplay, no more than two fielders can be positioned outside 30 yard circle (this is increased to three for the second and third Powerplay blocks). In the first 10 overs, it is also required that at least two fielders are in close catching positions.
The ICC have announced, as of 1 October 2007, with regard to Powerplays, that the captain of the fielding side may elect to position 3 fielders outside the 30 yard circle in one of the two 5-over Powerplays. The rule was first invoked in a match between Sri Lanka and England at Dambulla Stadium on 1 October 2007. Sri Lanka won the match by 119 runs. Currently both 2nd and 3rd powerplay will have 3 fielders outside 30 yard circle, and one powerplay is chosen by batting team.
The trial regulations also introduced a substitution rule that allowed the introduction of a replacement player at any stage in the match. Teams nominated their replacement player, called a Supersub, before the toss. The Supersub could bat, bowl, field or keep wicket; the replaced player took no further part in the game. Over the six months it was in operation, it became very clear that the Supersub was of far more benefit to the side that won the toss, unbalancing the game. Several international captains reached "gentleman's agreements" to discontinue this rule late in 2005. They continued to name supersubs, as required, but simply did not field them. On 15 February 2006, the ICC announced their intention to discontinue the Supersub rule on 21 March 2006.