Bits, Nibbles, and Bytes
In discussing the make of a binary number, we briefly covered the length of the number. The length of a binary number is the amount of 1's and 0's it has.
Common binary number lengths
Binary values are often grouped into a common length of 1’s and 0’s, this number of digits is called the length of a number. Common bit-lengths of binary numbers include bits, nibbles, and bytes (hungry yet?). Each 1 or 0 in a binary number is called a bit. From there, a group of 4 bits is called a nibble, and 8-bits makes a byte.
Bytes are a pretty common buzzword when working in binary. Processors are all built to work with a set length of bits, which is usually this length is a multiple of a byte: 8, 16, 32, 64, etc.
To sum it up:
Word is another length buzzword that gets thrown out from time-to-time. Word is much less yummy sounding and much more ambiguous. The length of a word is usually dependent on the architecture of a processor. It could be 16-bits, 32, 64, or even more.
Padding with leading zeros
You might see binary values represented in bytes (or more), even if making a number 8-bits-long requires adding leading zeros. Leading zeros are one or more 0’s added to the left of the most-significant 1-bit in a number. You usually don't see leading zeros in a decimal number: 007 doesn't tell you any more about the value of a number 7 (it might say something else).
Leading zeros aren't required on binary values, but they do help present information about the bit-length of a number. For example, you may see the number 1 printed as 00000001, just to tell you we're working within the realm of a byte. Both numbers represent the same value, however, the number with seven 0’s in front adds information about the bit-length of a value.