Pool is a family of cue sports played on a pool table with a cue ball and a set of object balls, usually involving the objective of legally pocketing particular balls according to the rules of the chosen discipline. The word pool does not describe one single universal game. It covers several related games, including eight ball, nine ball, ten ball, straight pool and other regional or historical variants.
Pool is therefore best understood as a category of cue sports rather than a single rule set. Most pool games use a table with six pockets, coloured and numbered object balls, and a cue ball that the player strikes with a cue. Players use the geometry of the table, ball control, angles, speed and spin to determine where balls travel and how the cue ball will be positioned for subsequent shots.
Pool developed from the broader history of cue sports that also includes billiards and snooker. The modern forms of pool emerged particularly strongly in the United States during the nineteenth and twentieth centuries, although cue sports themselves have much older European roots connected with indoor versions of lawn games. The term pool historically had associations with betting pools and public billiard rooms, where various cue games were played.
Over time, named disciplines developed with their own equipment specifications, ball sets and rules. American pool commonly uses balls numbered 1 through 15 plus a cue ball, while some forms of English pool use smaller tables, different ball sizes and a different set of colours and rules. Consequently, the precise meaning of pool depends strongly on geographical and sporting context.
The central physical principle of pool is collision control. The cue strikes the cue ball, which then transfers momentum to an object ball. The object ball travels towards a pocket if the player has selected an appropriate line and delivered the cue ball accurately. The cue ball then continues according to the angle and type of contact, with spin and speed influencing its subsequent path.
Players therefore have to think about both the current object ball and the next position of the cue ball. A successful pot can be strategically poor if the cue ball finishes in a location from which the next required shot is difficult. Advanced pool is consequently a positional game in which players construct sequences of shots rather than treating every pot as an isolated event.
Spin is one of the most important technical features of pool. A player can strike the cue ball away from its centre to produce top spin, back spin, left or right side spin, or combinations of these effects. Top spin tends to make the cue ball continue forward after striking an object ball, while back spin can cause it to draw backwards under appropriate conditions.
Side spin changes the cue ball's interaction with cushions and can alter the final path of the cue ball after collision. Players also control the speed of the stroke, which affects both object ball behaviour and cue ball travel. Advanced positional play depends on selecting an appropriate combination of contact point, cue speed, spin and angle.
Pool disciplines differ significantly in their objectives. In eight ball, players generally claim a group of seven coloured object balls and then attempt to pocket the eight ball after clearing their group. In nine ball, the balls numbered 1 through 9 are used and the cue ball must first contact the lowest numbered ball remaining, although other balls can be pocketed legally through combinations or caroms.
In straight pool, players can generally shoot any object ball into a called pocket and continue scoring until a predetermined target is reached. Ten ball resembles nine ball but normally requires the lowest numbered ball to be contacted first and uses stricter calling conventions. These differences mean that a statement about pool strategy can be accurate for one discipline but incorrect for another.
Pool is played recreationally and competitively in many countries. Commercial pool halls, clubs, pubs and private homes commonly provide tables for casual play, while organised competitions use standardised rules, referees and equipment specifications. Professional players may compete under organisations such as the World Pool Association and national governing bodies, with tournaments attracting international fields. Pool has also developed extensive coaching literature and technical analysis covering stroke mechanics, aiming systems, break techniques, pattern play, safety play and psychological preparation. Television and online streaming have expanded its audience, while high level players increasingly use detailed practice routines and video analysis to refine small differences in cue delivery and positional accuracy.
Pool terminology contains many words that can be confused with snooker or other cue sports. The break in pool usually means the opening shot that scatters the racked balls, whereas a snooker break normally means a scoring visit. A rack is the arrangement of object balls before the opening shot, although some traditions use rack as a verb for the process of arranging them.
A safety is a deliberate defensive shot intended to limit the opponent's options, a concept shared with snooker but implemented differently according to the rules of each discipline. A scratch usually refers to illegally pocketing the cue ball in many pool rulesets. These distinctions demonstrate why identifying the specific pool game is essential before applying a particular rule or strategy.
Pool is therefore a broad category of cue sports based on pocketing object balls while controlling the cue ball, but it cannot be reduced to one universal set of rules. Its defining characteristics include a pocketed table, cue ball, object balls, deliberate aiming, collision physics, positional play and discipline specific objectives. The most widely recognised forms include eight ball and nine ball, but many other variants exist.
The differences in rack arrangement, ball sequence, winning conditions, called shots, fouls and break requirements can be substantial. Understanding pool at an expert level therefore requires distinguishing the general physical principles shared by the family from the specific laws of the individual game being played.
