What's the difference between a word and byte?

Question

I\'ve done some research. A byte is 8 bits and a word is the smallest unit that can be addressed on memory. The exact length of a word varies. What I don\'t understand is wh

Answer 1

The exact length of a word varies. What I don't understand is what's the point of having a byte? Why not say 8 bits?

Even though the length of a word varies, on all modern machines and even all older architectures that I'm familiar with, the word size is still a multiple of the byte size. So there is no particular downside to using "byte" over "8 bits" in relation to the variable word size.

Beyond that, here are some reasons to use byte (or octet¹) over "8 bits":

1. Larger units are just convenient to avoid very large or very small numbers: you might as well ask "why say 3 nanoseconds when you could say 0.000000003 seconds" or "why say 1 kilogram when you could say 1,000 grams", etc.
2. Beyond the convenience, the unit of a byte is somehow as fundamental as 1 bit since many operations typically work not at the byte level, but at the byte level: addressing memory, allocating dynamic storage, reading from a file or socket, etc.
3. Even if you were to adopt "8 bit" as a type of unit, so you could say "two 8-bits" instead of "two bytes", it would be often be very confusing to have your new unit start with a number. For example, if someone said "one-hundred 8-bits" it could easily be interpreted as 108 bits, rather than 100 bits.

---

¹ Although I'll consider a byte to be 8 bits for this answer, this isn't universally true: on older machines a byte may have a different size (such as 6 bits. Octet always means 8 bits, regardless of the machine (so this term is often used in defining network protocols). In modern usage, byte is overwhelmingly used as synonymous with 8 bits.