Bit of Trivia: A Byte is the most basic storage type for most modern day programming languages. It is traditionally composed of 8 bits which are the smallest unit of storage(being able to hold either a 1 or 0, on or off, etc.). The byte was historically used to encode a single character of text in a computer. There have been variations but 8 bits=1 byte is the modern standard.
A Nybble is a grouping of bits, commonly in groups of 3 or 4 that are used to easily convert base 2 numbers into base 8 and base 16 respectively.
By current standards, a nybble is 4 bits used to represent a single hexadecimal digit. Because of this it is common to write binary numbers in groups of 4 for ease of readability(ex: 1010 1101 1001). Because of this, it is common to represent a byte, which is 8 bits of information, as 2 hexadecimal digits.
Interestingly both byte and nybble come from their homophones in the English language, bite and nibble. Where a nibble is a small bite; a nybble is also part of a byte.