Editing Curling (section)

== Gameplay ==
[[File:Curling Canada Torino 2006.jpg|thumb|At the [[2006 Winter Olympics]], [[Mark Nichols (curler)|Mark Nichols]] from Team Canada delivers a stone while his teammates look on, ready to begin sweeping. The curler uses his broom to help keep his balance during delivery.]]

The purpose of a game is to score points by getting stones closer to the house centre, or the "button", than the other team's stones.<ref>{{cite web |url=http://www.sportinglife360.com/index.php/curling-explained-to-non-curlers-16574/ |title=Curling Explained to non Curlers by Cameron Scott |work=Sporting Life 360 |date=14 February 2010 |access-date=10 February 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140209162800/http://www.sportinglife360.com/index.php/curling-explained-to-non-curlers-16574/ |archive-date=9 February 2014}}</ref> Players from either team alternate in taking shots from the far side of the sheet. An end is complete when all eight rocks from each team have been delivered, a total of sixteen stones. If the teams are tied at the end of regulation, often extra ends are played to break the tie. The winner is the team with the highest score after all ends have been completed (see [[#Scoring|Scoring]] below). A game may be conceded if winning the game is infeasible.

International competitive games are generally ten ends, so most of the national championships that send a representative to the World Championships or Olympics also play ten ends. However, there is a movement on the [[World Curling Tour]] to make the games only eight ends.<ref>{{cite web |title=Eight is Great! Asham World Curling Tour Events, Including Grand Slams, move to Eight-End Format |url=http://www.worldcurl.com/player.php?playerid=3587&view=News&articleid=7204 |website=World Curling Tour |access-date=18 September 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160919072427/http://www.worldcurl.com/player.php?playerid=3587&view=News&articleid=7204 |archive-date=19 September 2016 }}{{cbignore}}</ref> Most tournaments on that tour are eight ends, as are the vast majority of recreational games.

In international competition, each side is given 73 minutes to complete all of its throws. Each team is also allowed two minute-long timeouts per 10-end game. If extra ends are required, each team is allowed 10 minutes of playing time to complete its throws and one added 60-second timeout for each extra end. However, the "thinking time" system, in which the delivering team's game timer stops as soon as the shooter's rock crosses the t-line during the delivery, is becoming more popular, especially in Canada. This system allows each team 38 minutes per 10 ends, or 30 minutes per 8 ends, to make strategic and tactical decisions, with 4 minutes and 30 seconds an end for extra ends.<ref>{{cite web |url=http://www.curling.ca/about-the-sport-of-curling/getting-started-in-curling/rules-of-curling-for-general-play/ |title=Rules of Curling for General Play |work=Canadian Curling Association |date=October 2014 |access-date=20 November 2014 |url-status=dead |archive-url=https://web.archive.org/web/20141129140619/http://www.curling.ca/about-the-sport-of-curling/getting-started-in-curling/rules-of-curling-for-general-play/ |archive-date=29 November 2014 }}</ref> The "thinking time" system was implemented after it was recognized that using shots which take more time for the stones to come to rest was being penalized in terms of the time the teams had available compared to teams which primarily use hits which require far less time per shot.

=== Delivery ===
{{more citations needed section|date=February 2018}}
The process of sliding a stone down the sheet is known as the ''delivery'' or ''throw''. Players, with the exception of the skip, take turns throwing and sweeping; when one player (e.g., the [[Lead (curling)|lead]]) throws, the players not delivering (the [[Second (curling)|second]] and [[Third (curling)|third]]) sweep (see [[#Sweeping|Sweeping]], below). When the skip throws, the vice-skip takes their role.

The ''[[Skip (curling)|skip]]'', or the captain of the team, determines the desired stone placement and the required ''weight'', ''turn'', and ''line'' that will allow the stone to stop there. The placement will be influenced by the tactics at this point in the game, which may involve taking out, blocking, or tapping another stone.
* The ''weight'' of the stone is its velocity, which depends on the leg drive of the delivery rather than the arm.
* The ''turn'' or ''curl'' is the rotation of the stone, which gives it a curved trajectory.
* The ''line'' is the direction of the throw ignoring the effect of the ''turn''.

The skip may communicate the ''weight'', ''turn'', ''line,'' and other tactics by calling or tapping a broom on the ice. In the case of a takeout, guard, or a tap, the skip will indicate the stones involved.

Before delivery, the running surface of the stone is wiped clean and the path across the ice swept with the broom if necessary, since any dirt on the bottom of a stone or in its path can alter the trajectory and ruin the shot. Intrusion by a foreign object is called a ''pick-up'' or ''pick''.

[[File:hack.jpg|thumb|Players must push out of the ''hack'' to deliver their stones. 95% of hacks in use around the world are Marco Hacks, which were invented in the 1980s by [[Marco Ferraro]].<ref>{{cite news |url=https://www.pressreader.com/canada/ottawa-citizen/20100326/285164354536152 |title=Ferraro's hack innovation remains curling standard |work=Ottawa Citizen |via=[[PressReader]] |first=Darren |last=DeSaulniers |page=B5 |date=26 March 2010 |url-status=live |archive-url=https://web.archive.org/web/20170904020234/https://www.pressreader.com/canada/ottawa-citizen/20100326/285164354536152 |archive-date=4 September 2017}}</ref>]]
[[File:Outdoor curling on Stormont Loch - geograph.org.uk - 1655114.jpg|thumb|right|Outdoor curling on Stormont Loch.<ref>{{cite news |last=Bannerman |first=Gordon |title=Curling: Stormont Loch hosts outdoor bonspiel |url=https://www.dailyrecord.co.uk/sport/local-sport/curling-stormont-loch-hosts-outdoor-2747742 |access-date=20 February 2018 |agency=Daily Record |date=11 November 2013 |archive-date=21 February 2018 |archive-url=https://web.archive.org/web/20180221035646/https://www.dailyrecord.co.uk/sport/local-sport/curling-stormont-loch-hosts-outdoor-2747742 |url-status=live }}</ref> The stone is delivered from an iron crampit<ref>{{cite book |last=Syers |first=Edgar and Madge |title=The book of winter sports |date=1908 |publisher=Edward Arnold |location=London |page=29 |url=https://archive.org/stream/bookofwinterspor00syer#page/28/mode/2up/search/crampit |access-date=7 February 2021}}</ref> rather than the hack used indoors]]

The thrower starts from the ''hack''. The thrower's ''gripper'' shoe (with the non-slippery sole) is positioned against one of the hacks; for a right-handed curler the right foot is placed against the left hack and vice versa for a left-hander. The thrower, now ''in the hack'', lines the body up with shoulders square to the skip's broom at the far end for ''line''.

The stone is placed in front of the foot now in the hack. Rising slightly from the hack, the thrower pulls the stone back (some older curlers may actually raise the stone in this backward movement) then lunges smoothly out from the hack pushing the stone ahead while the slider foot is moved in front of the gripper foot, which trails behind. The thrust from this lunge determines the ''weight'', and hence the distance the stone will travel. Balance may be assisted by a broom held in the free hand with the back of the broom down so that it slides. One older writer suggests the player keep "a basilisk glance" at the mark.<ref>{{cite book |last=Kerr |first=John |title=History of curling, Scotland's ain game, and fifty years of the Royal Caledonian Curling Club |date=1890 |publisher=David Douglas |location=Edinburgh |page=402 |url=https://archive.org/stream/historyofcurling00kerruoft#page/n433/mode/2up/search/a+basilisk+glance |access-date=16 February 2018}}</ref>

There are two common types of delivery currently, the typical flat-foot delivery and the [[Manitoba tuck]] delivery where the curler slides on the front ball of their foot.<ref name="tuckers">{{cite news |title=Team of 'tuckers' |url=http://www.winnipegfreepress.com/sports/curling/team-of-tuckers-371331851.html |first=Paul |last=Wiecek |newspaper=[[Winnipeg Free Press]]|date=7 March 2016 |url-status=live |archive-url=https://web.archive.org/web/20160308115915/http://www.winnipegfreepress.com/sports/curling/team-of-tuckers-371331851.html |archive-date=8 March 2016}}</ref>

When the player releases the stone, a rotation (called the ''turn)'' is imparted by a slight clockwise or counter-clockwise twist of the handle from around the two or ten o'clock position to the twelve o'clock on release. A typical rate of turn is about {{frac|2|1|2}} rotations before coming to a rest.

The stone must be released before its front edge crosses the near hog line. In major tournaments, the "[[Eye on the Hog]]" sensor is commonly used to enforce this rule. The sensor is in the handle of the stone and will indicate whether the stone was released before the near hog line. The lights on the stone handle will either light up green, indicating that the stone has been legally thrown, or red, in which case the illegally thrown stone will be immediately pulled from play instead of waiting for the stone to come to rest.

The stone must clear the far hog line or else be removed from play (''hogged''); an exception is made if a stone fails to come to rest beyond the far hog line after rebounding from a stone in play just past the hog line.

=== Sweeping ===
{{more citations needed section|date=April 2014}}
[[File:Olympic Curling, Vancouver 2010 crop sweeping.jpg|thumb|The skip of Team Sweden joins the front end in sweeping a stone into the house at the [[2010 Winter Olympics]] in Vancouver]]

After the stone is delivered, its trajectory is influenced by the two sweepers under instruction from the skip. Sweeping is done for several reasons: to make the stone travel further, to decrease the amount of curl, and to clean debris from the stone's path.<ref>{{cite web |url=http://www.businessinsider.com/why-curlers-sweep-the-ice-2014-2 |title=Why Curlers Sweep the Ice |website=[[Business Insider]] |date=14 February 2014 |access-date=20 August 2017 |url-status=live |archive-url=https://web.archive.org/web/20170820010904/http://www.businessinsider.com/why-curlers-sweep-the-ice-2014-2 |archive-date=20 August 2017}}</ref> Sweeping is able to make the stone travel further and straighter by slightly melting the ice under the brooms, thus decreasing the friction as the stone travels across that part of the ice. The stones curl more as they slow down, so sweeping early in travel tends to increase distance as well as straighten the path, and sweeping after sideways motion is established can increase the sideways distance.

One of the basic technical aspects of curling is knowing when to sweep. When the ice in front of the stone is swept, a stone will usually travel both further and straighter, and in some situations one of those is not desirable. For example, a stone may be traveling too fast (said to have too much weight), but require sweeping to prevent curling into another stone. The team must decide which is better: getting by the other stone, but traveling too far, or hitting the stone.

Much of the yelling that goes on during a curling game is the skip and sweepers exchanging information about the stone's ''line'' and ''weight'' and deciding whether to sweep. The skip evaluates the path of the stone and calls to the sweepers to sweep as necessary to maintain the intended track. The sweepers themselves are responsible for judging the weight of the stone, ensuring that the length of travel is correct and communicating the weight of the stone back to the skip. Many teams use a ''[[Glossary of curling##s|number system]]'' to communicate in which of 10 zones the sweepers estimate the stone will stop. Some sweepers use stopwatches to time the stone from the back line or tee line to the nearest hog line to aid in estimating how far the stone will travel.

Usually, the two sweepers will be on opposite sides of the stone's path, although depending on which side the sweepers' strengths lie this may not always be the case. Speed and pressure are vital to sweeping. In gripping the broom, one hand should be one third of the way from the top (non-brush end) of the handle while the other hand should be one third of the way from the head of the broom. The angle of the broom to the ice should be such that the most force possible can be exerted on the ice.<ref>{{Cite journal|date=2009|title=The Sports Science of Curling: A Practical Review|journal=Medicine & Science in Sports & Exercise|volume=41|pages=3|doi=10.1249/01.mss.0000352606.48792.77|issn=0195-9131}}</ref> The precise amount of pressure may vary from relatively light brushing ("just cleaning" - to ensure debris will not alter the stone's path) to maximum-pressure scrubbing.

Sweeping is allowed anywhere on the ice up to the ''tee line''; once the leading edge of a stone crosses the tee line only one player may sweep it. Additionally, if a stone is behind the tee line one player from the opposing team is allowed to sweep it. This is the only case that a stone may be swept by an opposing team member. In international rules, this player must be the skip, but if the skip is throwing, then the sweeping player must be the third.

=== ''Burning'' a stone ===
Occasionally, players may accidentally touch a stone with their broom or a body part. This is often referred to as ''burning'' a stone. Players touching a stone in such a manner are expected to call their own infraction as a matter of [[#Good sportsmanship|good sportsmanship]]. Touching a stationary stone when no stones are in motion (there is no delivery in progress) is not an infraction as long as the stone is struck in such a manner that its position is not altered, and this is a common way for the skip to indicate a stone that is to be taken out.

When a stone is touched when stones are in play, the remedies vary<ref name="Rules"/> between leaving the stones as they end up after the touch, replacing the stones as they would have been if no stone were touched, or removal of the touched stone from play. In non-officiated league play, the skip of the non-offending team has the final say on where the stones are placed after the infraction.

=== Types of shots ===
[[File:CurlingLastStone.svg|thumb|Two ways to get the button with the last stone: a draw on the left (outturn for right-handed delivery), and a hit and roll on the right]]
Many different types of shots are used to carefully place stones for strategic or tactical reasons; they fall into three fundamental categories as follows:

''Guards'' are thrown in front of the house in the ''free guard zone'', usually to protect a stone or to make the opposing team's shot difficult. Guard shots include the ''centre-guard'', on the centreline, and the ''corner-guards'' to the left or right sides of the centre line. See ''Free Guard Zone'' below.

''Draws'' are thrown only to reach the house. Draw shots include ''[[Glossary of curling#Raise|raise]]'', ''[[Glossary of curling#Come-around|come-around]]'', and ''[[Glossary of curling#Freeze|freeze]]'' shots.

''Takeouts'' are intended to remove stones from play and include the ''[[Glossary of curling#Peel|peel]]'', ''[[Glossary of curling#Hit and roll|hit-and-roll]]'', and ''[[Glossary of curling#Double|double]]'' shots.

For a more complete listing, see [[Glossary of curling terms]].

=== Free guard zone ===
{{More citations needed section|date=May 2019}}
The ''free guard zone'' is the area of the curling sheet between the hog line and tee line, excluding the house. Until five stones have been played (three from the side without hammer and two from the side with hammer), stones in the free guard zone may not be removed by an opponent's stone, although they can be moved within the playing area. If a stone in the free guard zone is knocked out of play, it is placed back in the position it was in before the shot was thrown and the opponent's stone is removed from play. This rule is known as the ''five-rock rule'' or the ''free guard zone rule'' (previous versions of the free guard zone rule only limited removing guards from play in the first three or four rocks).<ref>{{Cite web|url=https://worldcurling.org/competitions/rules/|title=Rules of Curling|website=World Curling Federation|language=en-GB|access-date=2020-02-04|archive-date=16 February 2022|archive-url=https://web.archive.org/web/20220216194406/https://worldcurling.org/competitions/rules/|url-status=live}}</ref>

This rule, a relatively recent addition to curling, was added in response to a strategy by teams of gaining a lead in the game and then ''peeling'' all of the opponents' stones (knocking them out of play at an angle that caused the shooter's stone to also roll out of play, leaving no stones on the ice). By knocking all stones out the opponents could at best score one point, if they had the last stone of the end (called the [[Hammer (curling)|hammer]]). If the team peeling the rocks had the hammer they could peel rock after rock which would ''blank the end'' (leave the end scoreless), keeping the last rock advantage for another end. This strategy had developed (mostly in Canada) as ice-makers had become skilled at creating a predictable ice surface and newer brushes allowed greater control over the rock. While a sound strategy, this made for an unexciting game. Observers at the time noted that if two teams equally skilled in the peel game faced each other on good ice, the outcome of the game would be predictable from who won the coin flip to have last rock (or had earned it in the schedule) at the beginning of the game. The 1990 [[Tim Hortons Brier|Brier]] (Canadian men's championship) was considered by many curling fans as boring to watch because of the amount of peeling and the quick adoption of the free guard zone rule the following year reflected how disliked this aspect of the game had become.

The free guard zone rule was originally called the Modified Moncton Rule and was developed from a suggestion made by [[Russ Howard]] for the Moncton 100 cashspiel in [[Moncton]], New Brunswick, in January 1990. "Howard's Rule" (later known as the Moncton Rule), used for the tournament and based on a practice drill his team used, had the first four rocks in play unable to be removed no matter where they were at any time during the end. This method of play was altered by restricting the area in which a stone was protected to the free guard zone only for the first four rocks thrown and adopted as a four-rock free guard zone rule for international competition shortly after. Canada kept to the traditional rules until a three-rock free guard zone rule was adopted for the 1993–94 season. After several years of having the three-rock rule used for the Canadian championships and the winners then having to adjust to the four-rock rule in the World Championships, the [[Canadian Curling Association]] adopted the four-rock free guard zone in the 2002–03 season.

One strategy that has been developed by curlers in response to the free guard zone ([[Kevin Martin (curler)|Kevin Martin]] from Alberta is one of the best examples) is the "tick" game, where a shot is made attempting to knock (tick) the guard to the side, far enough that it is difficult or impossible to use, but still remaining in play while the shot itself goes out of play. The effect is functionally identical to peeling the guard, but significantly harder, as a shot that hits the guard too hard (knocking it out of play) results in it being replaced, while not hitting it hard enough can result in it still being tactically useful for the opposition. There is also a greater chance that the shot will miss the guard entirely because of the greater accuracy required to make the shot. Because of the difficulty of making this type of shot, only the best teams will normally attempt it, and it does not dominate the game the way the peel formerly did. [[Steve Gould (curler)|Steve Gould]] from Manitoba popularized ticks played across the face of the guard stone. These are easier to make because they impart less speed on the object stone, therefore increasing the chance that it remains in play even if a bigger chunk of it is hit.

With the tick shot reducing the effectiveness of the four-rock rule, the [[Grand Slam of Curling]] series of bonspiels adopted a five-rock rule in 2014.<ref>{{cite web |url=http://www.thegrandslamofcurling.com/curling/what-is-the-five-rock-rule/ |title=What is the five-rock rule? |publisher=Grand Slam of Curling |date=19 September 2017 |access-date=10 October 2018 |archive-date=11 October 2018 |archive-url=https://web.archive.org/web/20181011203817/http://www.thegrandslamofcurling.com/curling/what-is-the-five-rock-rule/ |url-status=live }}</ref> In 2017, the five-rock rule was adopted by the World Curling Federation and member organizations for official play, beginning in the 2018–19 season.<ref name="natpost20180203">{{cite news |url=https://nationalpost.com/sports/curling/curlings-new-five-rock-free-guard-zone-rule-designed-to-generate-offence |title=Curling's new five-rock free guard zone rule designed to generate offence |work=National Post |first=Murray |last=McCormick |date=3 February 2018 |access-date=10 October 2018}}</ref><ref name="curlcan20180615">{{cite web |url=https://www.curling.ca/blog/2018/06/15/thiessen-blog-five-rock-fgz-a-positive-change-for-curling/ |title=Thiessen Blog: Five-rock FGZ a Positive Change for Curling |publisher=Curling Canada |first=Nolan |last=Thiessen |date=15 June 2018 |access-date=10 October 2018 |archive-date=7 October 2018 |archive-url=https://web.archive.org/web/20181007111506/https://www.curling.ca/blog/2018/06/15/thiessen-blog-five-rock-fgz-a-positive-change-for-curling/ |url-status=live }}</ref>

=== Hammer === <!-- This section is linked from [[Hammer (disambiguation)]] -->
The last rock in an end is called the ''hammer'', and throwing the hammer gives a team a tactical advantage. Before the game, teams typically decide who gets the hammer in the first end either by chance (such as a coin toss), by a "draw-to-the-button" contest, where a representative of each team shoots to see who gets closer to the centre of the rings, or, particularly in tournament settings like the Winter Olympics, by a comparison of each team's win–loss record. In all subsequent ends, the team that did not score in the preceding end gets to throw second, thus having the hammer. In the event that neither team scores, called a ''blanked end'', the hammer remains with the same team. Naturally, it is easier to score points with the hammer than without; the team with the hammer generally tries to score two or more points. If only one point is possible, the skip may try to avoid scoring at all in order to retain the hammer the next end, giving the team another chance to use the hammer advantage to try to score two points. Scoring without the hammer is commonly referred to as ''stealing'', or ''a steal'', and is much more difficult.

=== Strategy ===
[[File:Curlingdiagram.svg|thumb|upright|Diagram of the play area in curling, showing the four-foot zone, corner guard, and centre line guard]]

Curling is a game of strategy, tactics, and skill. The strategy depends on the team's skill, the opponent's skill, the conditions of the ice, the score of the game, how many ends remain and whether the team has last-stone advantage (the ''hammer''). A team may play an end aggressively or defensively. Aggressive playing will put a lot of stones in play by throwing mostly draws; this makes for an exciting game and although risky the rewards can be great. Defensive playing will throw a lot of hits preventing a lot of stones in play; this tends to be less exciting and less risky. A good drawing team will usually opt to play aggressively, while a good hitting team will opt to play defensively.

If a team does not have the hammer in an end, it will opt to try to clog up the four-foot zone in the house to deny the opposing team access to the button. This can be done by throwing "centre line" guards in front of the house on the centre line, which can be tapped into the house later or drawn around. If a team has the hammer, they will try to keep this four-foot zone free so that they have access to the button area at all times. A team with the hammer may throw a ''corner guard'' as their first stone of an end placed in front of the house, but outside the four-foot zone to utilize the free guard zone. Corner guards are key for a team to score two points in an end, because they can either draw around it later or hit and roll behind it, making the opposing team's shot to remove it more difficult.

Ideally, the strategy in an end for a team with the hammer is to score two points or more. Scoring one point is often a wasted opportunity, as they will then lose last-stone advantage for the next end. If a team cannot score two points, they will often attempt to "blank an end" by removing any leftover opposition stones and rolling out; or, if there are no opposition stones, just throwing the stone through the house so that no team scores any points, and the team with the hammer can try again the next end to score two or more with it. Generally, a team without the hammer would want to either force the team with the hammer to only one point, so that they can get the hammer back, or "steal" the end by scoring one or more points of their own.<ref>{{cite web |title=Section 7 Basic Strategy |url=http://www.curlingschool.com/manual2007/Section7.html |website=The Curling Manual |access-date=16 February 2018 |archive-url=https://web.archive.org/web/20180225130258/http://www.curlingschool.com/manual2007/Section7.html |archive-date=25 February 2018 |url-status=dead }}</ref>

Large leads are often defended by displacing the opponent's stones to reduce their opportunity to score multiple points. However, a comfortably leading team that leaves their own stones in play becomes vulnerable as the opponent can draw around guard stones, stones in the house can be "tapped back" if they are in front of the tee line, or "frozen onto" if they are behind the tee line. A frozen stone is placed in front of and touching the opponent's stone and is difficult to remove. At this point, a team may opt for "peels"; throws with a lot of "weight" that can move opposition stones out of play.{{clear}}

=== Conceding a game ===
It is common at any level for a losing team to terminate the match before all ends are completed if it believes it no longer has a realistic chance of winning. Competitive games end once the losing team has "run out of rocks"—that is, once it has fewer stones in play and available for play than the number of points needed to tie the game.

=== Dispute resolution ===
[[File:Curling metering.jpg|thumb|Measuring which stone is closest to the centre of the house]]

Most decisions about rules are left to the skips, although in official tournaments, decisions may be left to the officials. However, all scoring disputes are handled by the vice skip. No players other than the vice skip from each team should be in the house while score is being determined. In tournament play, the most frequent circumstance in which a decision has to be made by someone other than the vice skip is the failure of the vice skips to agree on which stone is closest to the button. An independent official (supervisor at Canadian and World championships) then measures the distances using a specially designed device that pivots at the centre of the button. When no independent officials are available, the vice skips measure the distances.