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.
Crickets have a cosmopolitan distribution, being found in all parts of the world with the exception of cold regions at latitudes higher than about 55° North and South. They have colonised many large and small islands, sometimes flying over the sea to reach these locations, or perhaps conveyed on floating timber or by human activity. The greatest diversity occurs in tropical locations, such as in Malaysia, where 88 species were heard chirping from a single location near Kuala Lumpur. A greater number than this could have been present because some species are mute.
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.
Historically, cricket's origins are uncertain and the earliest definite reference is in south-east England in the middle of the 16th century. It spread globally with the expansion of the British Empire, leading to the first international matches in the second half of the 19th century. The game's governing body is the International Cricket Council (ICC), which has over 100 members, twelve of which are full members who play Test matches. The game's rules are held in a code called the Laws of Cricket which is owned and maintained by Marylebone Cricket Club (MCC) in London. The sport is followed primarily in the Indian subcontinent, Australasia, the United Kingdom, southern Africa and the West Indies, its globalisation occurring during the expansion of the British Empire and remaining popular into the 21st century. Women's cricket, which is organised and played separately, has also achieved international standard. The most successful side playing international cricket is Australia, which has won seven One Day International trophies, including five World Cups, more than any other country and has been the top-rated Test side more than any other country.
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.
The game on the field is regulated by the two umpires, one of whom stands behind the wicket at the bowler's end, the other in a position called "square leg" which is about 15–20 metres away from the batsman on strike and in line with the popping crease on which he is taking guard. The umpires have several responsibilities including adjudication on whether a ball has been correctly bowled (i.e., not a no-ball or a wide); when a run is scored; whether a batsman is out (the fielding side must first appeal to the umpire, usually with the phrase "How's that?" or "Owzat?"); when intervals start and end; and the suitability of the pitch, field and weather for playing the game. The umpires are authorised to interrupt or even abandon a match due to circumstances likely to endanger the players, such as a damp pitch or deterioration of the light.
Previous versions of the Spirit identified actions that were deemed contrary (for example, appealing knowing that the batsman is not out) but all specifics are now covered in the Laws of Cricket, the relevant governing playing regulations and disciplinary codes, or left to the judgement of the umpires, captains, their clubs and governing bodies. The terse expression of the Spirit of Cricket now avoids the diversity of cultural conventions that exist in the detail of sportsmanship – or its absence.
A skilled batsman can use a wide array of "shots" or "strokes" in both defensive and attacking mode. The idea is to hit the ball to the best effect with the flat surface of the bat's blade. If the ball touches the side of the bat it is called an "edge". The batsman does not have to play a shot and can allow the ball to go through to the wicketkeeper. Equally, he does not have to attempt a run when he hits the ball with his bat. Batsmen do not always seek to hit the ball as hard as possible, and a good player can score runs just by making a deft stroke with a turn of the wrists or by simply "blocking" the ball but directing it away from fielders so that he has time to take a run. A wide variety of shots are played, the batsman's repertoire including strokes named according to the style of swing and the direction aimed: e.g., "cut", "drive", "hook", "pull".
Cricket has close historical ties with Australian rules football and many players have competed at top levels in both sports. In 1858, prominent Australian cricketer Tom Wills called for the formation of a "foot-ball club" with "a code of laws" to keep cricketers fit during the off-season. The Melbourne Football Club was founded the following year, and Wills and three other members codified the first laws of the game. It is typically played on modified cricket fields.
Limited overs cricket is always scheduled for completion in a single day. There are two types: List A which normally allows fifty overs per team; and Twenty20 in which the teams have twenty overs each. Both of the limited overs forms are played internationally as Limited Overs Internationals (LOI) and Twenty20 Internationals (T20I). List A was introduced in England in the 1963 season as a knockout cup contested by the first-class county clubs. In 1969, a national league competition was established. The concept was gradually introduced to the other leading cricket countries and the first limited overs international was played in 1971. In 1975, the first Cricket World Cup took place in England. Twenty20 is a new variant of limited overs itself with the purpose being to complete the match within about three hours, usually in an evening session. The first Twenty20 World Championship was held in 2007. Limited overs matches cannot be drawn, although a tie is possible and an unfinished match is a "no result".