A "jump shot"
describes any shot where the cue ball is intentionally driven into the
air in a legal manner. It is not permissible in some games (e.g.
Snooker) and may be frowned upon or even forbidden in some venues as
attempts at it by unskilled players may cause damage to a table's cloth.
A legal jump shot requires that the cue ball be hit above center,
driving it down into the table, such that the ball will leave the table
surface on a rebound. All authoritative rule sources deem it illegal to
"scoop" under the cue ball with the tip of the cue to fling it into the
air (technically because it is illegal to contact the cue ball with the
ferrule of the cue, and because the cue ball is struck twice, both of
which are classic fouls).
Unintentional small jumps are ubiquitous to billiards. In most billiards shots, a player's cue is slightly elevated. Whenever a ball is struck with an elevated cue, a jump, no matter how slight, occurs. An oft-used way to illustrate this principle is to lay a coin on the table approximately an inch in front of the cue ball. When shot very softly, the player will audibly hear the coin being struck and see the cue ball's reaction to that collision. When the same shot is performed with any degree of speed no sound or collision is evident, and it is clear that the coin is being jumped.
Unintentional small jumps are ubiquitous to billiards. In most billiards shots, a player's cue is slightly elevated. Whenever a ball is struck with an elevated cue, a jump, no matter how slight, occurs. An oft-used way to illustrate this principle is to lay a coin on the table approximately an inch in front of the cue ball. When shot very softly, the player will audibly hear the coin being struck and see the cue ball's reaction to that collision. When the same shot is performed with any degree of speed no sound or collision is evident, and it is clear that the coin is being jumped.