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 what's the point of having a byte? Why not say 8 bits?

I asked a prof this question and he said most machines these days are byte-addressable, but what would that make a word?

Answer 1

A word is the size of the registers in the processor. This means processor instructions like, add, mul, etc are on word-sized inputs.

But most modern architectures have memory that is addressable in 8-bit chunks, so it is convenient to use the word "byte".

Answer 2

A group of 8 bits is called a byte ( with the exception where it is not :) for certain architectures )

A word is a fixed sized group of bits that are handled as a unit by the instruction set and/or hardware of the processor. That means the size of a general purpose register ( which is generally more than a byte ) is a word

In the C, a word is most often called an integer => int