A die is a physical object designed to rest randomly on one of a number of sides after being thrown.
Notation[]
In die notation, the number preceding the letter "d" indicates the number of dice to throw. One die is thrown if omitted. The number after the letter "d" refers to the number of sides on the die or dice to be thrown. Multiple dice may be thrown simultaneously or consecutively; the results of each die are added together.
Dice in 4th edition[]
In 4th edition Dungeons & Dragons, die rolls may require the use of any of the following.
| Notation | Meaning |
|---|---|
| d4 | a four-sided die, usually a regular tetrahedron |
| d6 | a six-sided die, usually a cube |
| d8 | an eight-sided die, usually a regular octahedron |
| d10 | a ten-sided die, usually a pentagonal trapezohedron |
| d12 | a twelve-sided die, usually a regular dodecahedron |
| d20 | a twenty-sided die, usually a regular icosahedron |
By convention, the 10 face of a ten-sided die is usually marked "0" for compatibility with percentile rolls (see below). In non-percentile rolls, "0" on a d10 means 10.
In D&D, die size refers to the number of sides on the die rather than its physical volume. For example, a d8 is one die size larger than a d6, even though a six-sided die often has a larger volume than an eight-sided one.
Players and Dungeon Masters are typically expected to each bring a full set of the above six dice to game sessions. A player, for convenience, might bring additional dice of the same die size, for example, multiple dice corresponding to the player character's weapon die if the character often uses weapon attack powers. Some Dungeon Masters, especially in online play, allow players to roll simulated dice with a computer application. Some gaming groups might pool their dice together.
Individual dice of all six sizes, as well as sets including all six sizes, are commonly available at gaming and hobby retailers. Die sets usually include an additional ten-sided die marked with double digit multiples of ten. The two ten-sided dice can be rolled and added together as a percentile (d100) roll, with the "0" on the single digit die meaning 0, except "00" and "0" together means 100. Percentile rolls are not common in 4th edition D&D.