In curling, also known as "chess on ice," the object of the game is to score more points than your opponent by strategically delivering stones into the house and preventing your opponent from scoring. In an end of curling, each team has eight stones (five in mixed doubles curling, with a sixth pre-placed stone) to place stones in the house (the scoring area) while keeping the opposing team from scoring simultaneously.

To accomplish this, teams must use their curling stones in a strategic manner to score within the ten ends of regulation play (eight ends in mixed doubles).

Shot selection

The strategy of curling mainly involves shot selection. There are several different types of shots:

Draw: A shot designed to stop inside or in front of the house (the concentric circles at the end of the rink). This is the basic scoring shot.

Freeze: A form of a draw that stops in front of another rock

Guard: A shot that stops in front of the house and is intended to prevent the opponent from hitting a stone in the house

Hit-and-roll: Generally, a shot designed to take out an opponent’s rock and then roll the shot rock to a designated spot. It also is possible to play a hit-and-roll off the team’s own rock.

Peel: A shot designed to remove another stone, as well as the shot rock

Raise: A type of draw designed to bump a rock to another position

Takeout: A shot that removes an opponent’s stone from play. A takeout designed to remove a guard is called a "peel."

It’s important to realize that these are just the basic shots. At Olympic-level competition, a shot might be a combination of several of the above. For instance, a “raise-takeout” would be hitting a stone in play and bumping that stone into another stone, which is taken out of play.

In addition to picking the type of shot, the skip also directs his teammate throwing the stone whether to play an in-turn or an out-turn. A player executes an in-turn by turning the inside of his palm toward his body when releasing the stone. A player executes an out-turn by turning the outside of his palm away from his body.

Stones curve, or curl, as they proceed down the ice – which is where the sport derives its name. Players impart spin on the stone using the handle; the curl allows for better control and also provides a way to shoot around other stones. For a right-handed player, an out-turn curls right to left and an in-turn curls left to right. How the stones are positioned on the ice dictates which type of shot the skip calls.

Playing with the lead

In addition to types of curling shots, strategies can differ on whether a team has a lead or not.

If a team has a significant lead going into the final few ends, it usually will play defensively. The team with the lead plays lots of takeout shots and generally tries to keep the sheet free of stones. The idea is that if the game is played “clean,” with few stones on the ice, there is less of a chance to get into trouble and allow the opponent to score several points and get back in the game.

If a team is behind by more than a few points going into the final ends, it plays the exact opposite strategy, getting as many rocks on the ice as possible, and thus creating a situation where the team can score multiple points during a single end. This strategy is made possible by the free guard zone rule, which refers to the area between the hogline and the house. During the first four stones of an end, no stone in this area may be removed from play by the opposition.

The hammer

The last shot of an end is called the hammer. The team that shoots last has the advantage, and a team sometimes is willing to give up a point to the other team to secure the hammer for the next end. The team that has earned one or more points shoots first in the next end, while the team that earned zero points receives the hammer.

Additionally, the team with the hammer sometimes will “blank” the end. This means instead of taking a single point in the end, the team clears the house so no one scores, thus keeping the hammer for the next end. It is considered a victory for the team without the hammer if it makes the other team only take one point. In most cases, the team with the hammer would rather keep the hammer than score one point. A team rarely will blank an end if it has the opportunity to score two or more points.
 

After a stone is thrown, players are allowed to sweep the ice in front of the stone with a curling broom. Sweeping clears the ice of any debris that might slow the stone down or send it off course. Sweeping also melts a thin layer of ice that reduces friction and thus increases the distance the rock travels. 

There are many different sweeping techniques used in curling that impact the speed and direction of a curling stone when delivered:

Press sweeping: The press technique is one of the most common techniques used in sweeping where an athlete uses their body weight to press down on the broom while not moving the head of the broom in front of the stone. By using body weight as the main source of power, sweepers conserve energy while using fast sweep strokes that drastically can increase the distance a stone travels while keeping the stone's trajectory straight.

Directional sweeping: Directional sweeping changes the trajectory of a rock. To straighten a rock, the athlete hugs the inside line of a curl with their body angled at a 45-degree line to the line of delivery, driving the broom away from their body. To add more curl, athletes stand on the outside line of the curl and sweep away from their body.

Number of sweepers: When an athlete delivers the stone, two other members of the team may sweep to change the trajectory of the stone. Many teams will opt to use both sweepers to speed up a stone, but some teams will use one sweeper to affect the direction of the stone more effectively.

In the order of delivering stones, the first player is known as the lead; they are followed by the second, then the third (who often is the vice-skip), and finally the skip, who is the team leader. 

The lead is in charge of opening up the game and each end with important shots, typically by drawing guards to throw draw shots around, which sets up the rest of the end for a team. Normally, leads are the strongest sweepers on the team and sweep the remaining six shots during an end.

The player in second position assists the lead with sweeping the final four shots of a round and sweeps during the lead's first two shots. They throw the third and fourth shots in a curling end.

The third, typically acting as the vice skip, throws the sixth and seventh shots during gan end and helps their teammates with aim by standing in the house and pointing where to throw the curling stones.

Along with taking the final shots of the match, the skip directs the team’s strategy and shot selection. If the beginning of an end goes well, it puts less pressure on a skip's final two shots. The skip goes last in case an end gets out of hand, requiring the skip to make a tricky shot to get out of a jam or a scoring threat from the opposition.

Strategy vastly differs in mixed doubles curling compared to men's and women's curling because of the limited number of ends in a match, the fewer stones thrown during an end and the pre-positioned stones unique to the mixed doubles discipline.

In mixed doubles curling, there only are eight ends of regulation where teams have an opportunity to score as opposed to the ten ends in men's and women's curling. Whereas in men's and women's curling each teammate throws two stones for a total of eight stones thrown per team during an end, each team in mixed doubles curling throws five stones along with a pre-positioned stone placed on the sheet before each end. 

The position of each team's pre-positioned end depends on whichever team has the hammer (the team throwing last in the end) and only can be placed in specific areas of the sheet following curling rules. In typical play, the team without the hammer will have a center line guard placed as their pre-positioned stone, where the team with the hammer places a stone where the center line intersects the back of the four-foot circle in the house.

While the team with the hammer must place their stone on the back of the four-foot circle, the team without the hammer has three options on the center line to place their guard. The team decides where to place the stone based on the conditions of the ice. Typically, the more “swingy” the ice is, the lower a team will place a guard (closer to the house) to prevent the hammer team from curling a stone into the house effectively.

Additionally, there is no free guard zone in mixed doubles curling, which is the area in men’s and women’s curling from the hogline to the tee line (excluding the front half of the house) where an opposition stone cannot be removed out of play until the sixth stone has been thrown (the third hammer stone). Instead, no stone may be removed from play - both team stones and opposition stones - until the fourth stone (second hammer stone) is thrown.

Mixed doubles introduces an event unique to the discipline: the power play. Once per game during regulation ends when a team has possession of the hammer, it can enact the power play, allowing the team to pick the position of both teams' pre-positioned stones. The hammer stone moves from the four-foot circle to the intersection of the front of the tee line and the meeting of the eight and 12-foot circles. The non-hammer team’s center line guard stone is moved to be in line with the hammer stone, thus clearing the center of the sheet and giving the hammer team a big advantage to score points in an end.

With only one power play per game, teams carefully must decide when to enact a power play. Typically, the power play is used when a team needs a big scoring boost or is attempting to protect a late lead.

Ice has a dramatic effect on how curlers sweep the ice as well as where stones are placed on the sheet, varying in speed and the weight of the ice. Throughout a curling match, ice conditions change due to sweeping and delivering stones on a sheet. Experienced curlers learn how to handle different ice conditions and adapt their play style throughout a match.

If a curler observes the ice playing "fast" and carrying the stone further down a sheet, they have to adjust the way the stone is thrown to adjust to the conditions and help out the sweepers. Fast or slow ice affects how much a sweeper needs to sweep in front of a curling stone; typically, athletes must sweep more vigorously if the ice is playing slow to control the desired distance.

Curlers describe ice conditions as "swingy" if the stones tend to curl more profoundly than on straight or heavy ice conditions, causing both the curler delivering the stone to adjust the angle and rotation applied, while the sweepers must prepare to sweep more or less depending on how straight the ice is playing.

Team communication is vital in all curling disciplines to get the best results during a match, whether deciding on where to aim a stone in an end or while sweeping.

To predict the distance or weight where a curler believes a stone will end up on the sheet, curlers use a number system to indicate to sweepers where they think the rock will travel. Numbers range from 1-10, starting from the hog line and ending at the back line, with "7" indicating that the rock will end up in line with the button, or center of the house. Curlers can be heard shouting calls to teammates depending on where they think a stone will end up, indicating to a sweeper if they should continue to brush the ice or leave the stone alone.

To be successful regarding weight judgement when a stone is delivered, all curling athletes on a team must be in sync with the calls and trust the judgement of the skip and vice skip when making decisions during an end.