One-day cricket is all about scoring quickly - it's the fielding side's job to keep the runs down and pick up wickets.
Unlike Test cricket, the fielders are spread out to save the runs.
In July 2005, the International Cricket Council (ICC) announced changes to the way one-day cricket is played.
Before that time, for the first 15 overs, nine fielders, including the bowler and the wicket-keeper, had to be inside a 30-yard (27.5m) circle when the ball was bowled.
The circle was marked out by markers five yards (4.5m) apart, so the fielders - and umpires - knew where to stand.
However under the new rules introduced in 2005 called Powerplays, the fielding restrictions are replaced by three blocks totalling 20 overs.
Powerplays are signalled by the umpire
During the first 10 overs, now known as Powerplay 1, only two fielders may be outside the fielding circle and at least two must be in catching positions.
Powerplay 2 and Powerplay 3 are five-over spells in which only three fielders may be outside the fielding circle, but there are no requirements about close catchers. They must be taken within the 50-over innings.
The fielding side decides when to take one of these powerplays, and in a rule change introduced in October 2008, the batting side decides when the other powerplay is taken.
A powerplay can only be invoked before the start of an over, and the umpire informed. The umpire will signal the start of the fielding side's choice of powerplay by waving his arm in a circular motion - and indicate a powerplay chosen by the batting side by waving his arms in a circle and then clapping his hands above his head.
Usually the fielding team will start with a third man and a fine leg to give the bowler protection on the off and leg side.
With a brand new ball the bowlers should get movement, so you'll usually see a couple of slips and a gully to snap up those edges.
The team's best - and quickest - fielders will often be at point and the covers.
Batsmen will be looking to drop the ball into gaps for quick singles, so it's up to these two to close down the space quickly and force run-outs.
With only two fielders outside of the inner circle, the batsman can smash the bowlers past the fielders for those boundaries and sixes in front of the wicket.
The fielding captain only needs four players inside the circle, plus the bowler and wicket-keeper, when the ball is bowled.
This means they can spread the field to protect the boundaries and save those precious runs.
But it's not as easy as that.
The fielding team is allowed a maximum of five fielders on the leg side, so if your bowlers are spraying the ball all over the place, you're in trouble.
The two opening bowlers will bowl roughly five to six overs each, leaving them a few at the end when the pressure is on.
But it's when the second and third string bowlers come on that the field really starts to spread.
These are usually batsmen who can bowl a bit but are prone to deliver a few gifts.
So for safety, a captain will usually push mid-on, mid-off and mid-wicket right back onto the boundary.
They also have the option of a deep point or square leg, depending on how quickly the batsmen are scoring.
The off-side field will be spread too, with a deep cover sweeping the boundary for drives and cuts.
And both mid-on and mid-off will be pushed right back on the boundary too.
So there's plenty of quick singles on offer for the batsmen to keep the scores ticking over.
But they're after the big runs, so the gaps between deep cover and long off - as well as deep mid-wicket and long on - are the main targets.