Fielding

All eleven players on the fielding side take the field together. One of them is the wicket-keeper aka "keeper" who operates behind the wicket being defended by the batsman on strike. Wicket-keeping is normally a specialist occupation and his primary job is to gather deliveries that the batsman does not hit, so that the batsmen cannot run byes. He wears special gloves (he is the only fielder allowed to do so), and pads to cover his lower legs. Owing to his position directly behind the striker, the wicket-keeper has a good chance of getting a batsman out caught off a fine edge from the bat. He is the only player who can get a batsman out stumped.
Apart from the one currently bowling, the other nine fielders are tactically deployed by the team captain in chosen positions around the field. These positions are not fixed but they are known by specific and sometimes colourful names such as "slip", "third man", "silly mid on" and "long leg". There are always many unprotected areas.
The captain is the most important member of the fielding side as he determines all the tactics including who should bowl (and how); and he is responsible for "setting the field", though usually in consultation with the bowler.
In all forms of cricket, if a fielder gets injured or becomes ill during a match, a substitute is allowed to field instead of him. The substitute cannot bowl, act as a captain or keep wicket. The substitute leaves the field when the injured player is fit to return.