A fielding captain's job is to get the opposition out for as few runs as possible.
To do this, they need to set fields which will help to take wickets and stop the flow of runs.
Unfortunately these two things don't go hand-in-hand, so a captain must either sacrifice runs to get wickets or risk taking fewer wickets to stop runs.
A lot of this depends on the bowler.
If a captain has a good opening bowler who can move the ball around, they'll set an attacking field with lots of close catchers around the bat to take wickets.
But if the runs are coming too quickly, a captain can move fielders to the boundary to stop the big shots.
And they can also set different fields for different batsman, especially if they like hitting in one particular area.
Test match fields are completely different from one-day fields too.
So every situation requires a different field - one of the many things that make the game of cricket so exciting.
~RS~q~RS~~RS~z~RS~33~RS~)