Six Sided Dice
The d6 dice is a platonic solid, the cube, Additionally, six sided dice are the most common dice type in gaming. They are used in everything from casinos to board games to roleplaying games. In fact, several RPGs that use nothing but the six sided dice for all rolls.
Within the gaming industry the d6 comes as part of a standard DND dice set with numbers on the faces, in sets of 12 with pips for numbering, and in sets of 36 smaller dice (12mm instead of the standard 16mm) with pips for numbering. The only way to get larger quantities of d6s with numbers instead of pips is to purchase them individually.
Casino-grade six sided dice must be manufactured with incredibly precise tolerances. They do this to ensure they are nearly perfectly possible. The dice we use in RPGs are made through traditional plastic injection molding and tumbling, making them 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 found are about 4,000 years old, found in Egyptian tombs. Six-sided dice have been found in ancient Chinese excavations and in thousand year old Viking burial mounds.