The most famous player of the 19th century was W. G. Grace, who started his long and influential career in 1865. It was especially during the career of Grace that the distinction between amateurs and professionals became blurred by the existence of players like him who were nominally amateur but, in terms of their financial gain, de facto professional. Grace himself was said to have been paid more money for playing cricket than any professional.
The Laws state that, throughout an innings, "the ball shall be bowled from each end alternately in overs of 6 balls". The name "over" came about because the umpire calls "Over!" when six balls have been bowled. At this point, another bowler is deployed at the other end, and the fielding side changes ends while the batsmen do not. A bowler cannot bowl two successive overs, although a bowler can (and usually does) bowl alternate overs, from the same end, for several overs which are termed a "spell". The batsmen do not change ends at the end of the over, and so the one who was non-striker is now the striker and vice-versa. The umpires also change positions so that the one who was at "square leg" now stands behind the wicket at the non-striker's end and vice-versa.
If a fielder is injured or becomes ill during a match, a substitute is allowed to field instead of him, but the substitute cannot bowl or act as a captain. The substitute leaves the field when the injured player is fit to return. The Laws of Cricket were updated in 2017 to allow substitutes to act as wicket-keepers, a situation that first occurred when Mumbai Indians' wicket-keeper Ishan Kishan was injured in a match on 18 April 2018.
There are ten ways in which a batsman can be dismissed: five relatively common and five extremely rare. The common forms of dismissal are bowled, caught, leg before wicket (lbw), run out and stumped. Rare methods are hit wicket, hit the ball twice, obstructing the field, handled the ball and timed out. The Laws state that the fielding team, usually the bowler in practice, must appeal for a dismissal before the umpire can give his decision. If the batsman is out, the umpire raises a forefinger and says "Out!"; otherwise, he will shake his head and say "Not out". There is, effectively, an eleventh method of dismissal, retired out, which is not an on-field dismissal as such but rather a retrospective one for which no fielder is credited.
Red parasitic mites sometimes attach themselves to the dorsal region of crickets and may greatly affect them. The horsehair worm Paragordius varius is an internal parasite and can control the behaviour of its cricket host and cause it to enter water, where the parasite continues its lifecycle and the cricket likely drowns. The larvae of the sarcophagid fly Sarcophaga kellyi develop inside the body cavity of field crickets. Female parasitic wasps of Rhopalosoma lay their eggs on crickets, and their developing larvae gradually devour their hosts. Other wasps in the family Scelionidae are egg parasitoids, seeking out batches of eggs laid by crickets in plant tissues in which to insert their eggs.
Subject to certain variations, on-field clothing generally includes a collared shirt with short or long sleeves; long trousers; woolen pullover (if needed); cricket cap (for fielding) or a safety helmet; and spiked shoes or boots to increase traction. The kit is traditionally all white and this remains the case in Test and first-class cricket but, in limited overs cricket, team colours are worn instead.