From Glitch City Laboratories
"HEX" and "hex" redirect here. For another use of the term, see identifier.
The hexadecimal or base sixteen number system has the number sixteen as its base. The hexadecimal number system has few day-to-day uses and is usually used only in the mathematics or computer science fields. Hexadecimal numbers have the digits 0 through 9 and A through F (corresponding to decimal values ten through fifteen).
Hexadecimal numbers are used to represent bytes, which can hold a value of 0 through 255. Two hexadecimal digits represent a byte; FF in hexadecimal is equal to 255 in decimal.
In the Pokémon glitch community, hexadecimal is the preferred system for identifiers. As such, the term "HEX" is synonymous with "identifier." Hexadecimal identifiers are used in cheat codes for cheating devices. In the first two generations of Pokémon games, identifiers were one byte long and thus had a maximum value of 255. In later generations, they are two bytes long.