The stick used to hit billiard balls, called a billiards cue, is different in some ways from the typical pool cue. Compared with pool cues, billiard cues are often shorter, with a shorter end cap (called a ferrule), a fatter bottom portion where the back hand grips the stick (called a butt), a wooden screw in the middle rather than one of metal or plastic, and a smaller tip diameter. These features make the billiard cue stiffer. This stiffness helps players in striking the larger and heavier billiard balls as compared with pool balls. The stiffness also acts to reduce an effect called "deflection" (sometimes called "squirt"). Deflection is an undesirable effect from the use of sidespin. Sidespin is spin placed on a ball by striking it not at its center but off to one side of its center, causing it to spin as it travels down the table. Deflection causes a ball to travel not in a straight line in the direction it was struck.
Underneath the cloth of billiard tables is a very hard rock called slate. The slate bed of a billiard table is often heated to about 5 °C/9 °F above room temperature, which helps to keep moisture out of the cloth to aid the balls rolling and rebounding in a consistent manner, and generally makes a table play faster. A heated table is required under international carom rules and is an important requirement for the games of three-cushion billiards and artistic billiards. Heating table beds is an old practice. Queen Victoria of England (1819–1901) had a billiard table that was heated using zinc tubes, At that time, though, the reason for the heating was different. The heat was used to keep ivory balls from going out of shape (warping). The first use of electric heating was for a tournament in the game of "18.2 balkline", that was held in December 1927 between two players: Welker Cochran and Jacob Schaefer, Jr. "The New York Times" announced it with fanfare: "For the first time in the history of world's championship balkline billiards a heated table will be used ..."
Straight rail, sometimes called carom billiards, straight billiards, the three-ball game, the carambole game, and the free game in Europe, is thought to date to the 1700s. No exact time of origin is known though. It was called French caroms, French billiards or the French game in early times, taking those old names from the French who made the game popular. The object of straight rail is simple: one point, called a "count", is scored each time a player's cue ball makes contact with both object balls (the second cue ball and the third ball) on a single strike of the cue ball. Winning is achieved by reaching a certain number of points, agreed to between the players to be the winning number.
When straight rail was first invented there was no restriction on the way points were scored. However, the technique of "crotching", meaning to have two balls right next to each other on the area of one of the table's four corners where the rails meet—the "crotch"—made scoring a lot easier. This resulted in an 1862 rule which allowed only three counts before at least one ball had to be sent away from the corner in order to legally score another point. Techniques continued to develop which increased counts greatly despite the crotching ban. One of these techniques is called "nursing", and made scoring much easier. A "nurse" is a series of shots where the balls are kept very close together, allowing a player to score off of them with very soft strokes without changing their positions much, so the scoring can continue. The most important of these nurse techniques, called the "rail nurse", involves nudging the balls down a rail, moving them just a few centimeters on each score and keeping them close together and positioned at the end of each stroke in the same or near the same arrangement so that the rail nurse can be repeated.
Professional straight rail in the United States was only seen for six years, from 1873 to 1879. It was followed by a game designed to reduce the use of the rail nurse so that spectators would not be bored by watching it. Today, straight rail play is not very common in the U.S. but it still popular in Europe, where it is thought to be a good practice game for balkline and three-cushion billiards. Europe hosts professional competitions, known as "pentathlons" after the ancient Greek Olympic competitions, in which straight rail is one of five billiards games at which players compete. The other four are called 47.1 balkline, cushion caroms, 71.2 balkline and three-cushion billiards.
A new game appeared in 1879, called the champion's game or limited-rail. The champion's game is considered an in-between game—between straight rail and balkline—and was designed to stop the rail nurse. The game uses diagonal lines—balklines—drawn at the table's corners to indicate that if balls were inside those lines, points could not be scored, thus "cutting off four triangular spaces in the four corners, [taking] away 28 inches [711 mm] of the 'nursing' surface of the end rails and 56 inches [1422 mm] on the long rails." Despite its differences from straight rail, the champion's game only expanded the areas of the table where many points in a row could be scored before the balls had to be moved to a new position. This was not sufficient to stop nursing.
Balkline came after the champion's game. It added more rules to stop nursing techniques. There are many varieties of balkline, but all divide the table into marked regions called "balk spaces". The balk spaces define areas of the surface of the table where a player may only score up to a certain number of points while the object balls are within that region.
In the balkline games, rather than drawing balklines a few inches from the corners as was done in the champion's games, the entire table is divided into rectangular spaces. This is done by drawing balklines a certain distance across the length and the width of the table. The lines are drawn a number of inches parallel from each rail. This divides the table into eight rectangular areas called "balk spaces". Additionally, rectangles are drawn where each balkline meets a rail, called "anchor spaces". The anchor spaces were added to the game to stop nursing techniques that developed especially for the challenges of balkline without them.
Generally, the differences between one balkline game and another are defined by two different things: 1) where the balkines are drawn on the table, and 2) the number of points that are allowed in each balk space before at least one ball must leave that region of the table. Balkline games are named by giving two numbers that tell us about the spacing used and how many points can be scored in the balk spaces. The first number tells us how many inches from the rail the balkine will be drawn. The second number after a "dot", indicates the number of points that can be scored in the balk spaces before the balls must leave it (that number is always either one or two). So, for example, the name "18.2 balkline", tells us that balklines are drawn distant from each rail, and only two points are allowed in a balk space before a ball must leave that area.
Over its history balkline has had many variations including 8.2, 10.2, 12.2, 13.2, 12½.2, 14.1, 14.2, 18.1, 18.2, 28.2, 38.2, 39.2, 42.2, 45.1, 45.2, 47.1, 47.2, 57.2 and 71.2 balkline. In its different forms, balkline was the main carom game played from 1883 to the 1930s. After that, other carom games became more popular. This is especially true of three-cushion billiards. Balkline is not very common in the U.S., but remains popular in Europe and the Far East.