In snooker, the black ball is worth 7 points when legally potted.
The black is the highest-value ball on a standard snooker table. During the main scoring phase, players normally pot a red first and then choose a colour. Potting the black after a red produces the largest possible colour score, so players often try to leave the cue ball in position for another black.
The colours have fixed values: yellow is 2, green 3, brown 4, blue 5, pink 6 and black 7. Reds are worth 1 point each. After the last red is potted, the colours must be cleared in ascending value, from yellow through black, so the black is the final scoring ball in a normal frame.
The black also matters tactically. A close frame can turn on a single black, and the phrase “a six-seven” is sometimes used informally for the difference between a pink and a black. A black potted from a penalty situation is scored differently from an ordinary colour after a red.