Six Sided Dice
The d6 is a platonic solid known as, you guessed it, a cube. The six-sided die is the most common type of die used in the world of gaming. They are used in everything from casinos to board games to role-playing games. In fact, several different RPGs use nothing but six-sided dice.
Within the TTRPG industry, the d6 is a part of three different dice sets and, as such, has three similar yet different forms. Firstly, the d6 is a part of the standard D&D dice set. Each die face contains a single number. Second is the 12d6 dice set. Each die face displays pips (small dots) rather than written numbers. Lastly is the 36d6 dice set. Like the 12d6 dice set, the dice in a 36d6 dice set use pips. Unlike the 12d6 dice set, however, dice in a 36d6 dice set are smaller than standard (12mm instead of the usual 16mm).
Casino-grade d6 must be manufactured with incredibly precise tolerances. This is done to ensure that each die is as perfect as possible, ensuing no dice has an imbalanced roll. The dice we use for RPGs are made using the traditional plastic injection molding and tumbling process, making the rolls produced less truly random. However, they are considered "balanced enough." In fact, it can take thousands of rolls before the difference becomes statistically significant. In other words, close enough for gaming purposes.
The oldest cubical dice discovered are about 4,000 years old and were found in Egyptian tombs. Six-sided dice have been found in ancient Chinese excavations and in thousand-year-old Viking burial mounds.