Nibble: a set of four bits

A nibble- also spelled nybble and nyble- is a set of four bits, or half an octet (the standard length of a byte). Two nybbles always equal one byte.

Interestingly, a nybble has 16 possible combinations (2^4) which is the same as a single digit in hexadecimal. Hence another name for a nibble is a hex digit.

Finally, programmers sometimes call nybbles quad bits because they are made up of four parts.

The name nibble comes from a pun on its size (“half a byte”) and the odd spelling is simply how some people match it up with the vowels present in byte.

They are used much of the time as a way to make debugging and computation faster and easier, because reserving the rightmost digit for a symbol allows the digits to be packed into five bytes, which are visible in a hex dump (a hexadecimal view of computer data on screen).

This is all done by splitting an 8 bit byte into two parts and using each nibble to represent a single decimal digit.

Then, in the hex dump, every two nibbles represents one decimal digit.  There are 2- bit groupings of bits, though it is rare to hear them referred to as semi- nibbles or half- nibbles.

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