Bits and Bytes
The fundamental unit of information in the binary digital computer is the bit (BInarydigiT).
A bit has two values that we call 0 and 1, low and high, true and false, clear and set, and so on.
We use bits because they are easy to “make” and “read”, not because of any intrinsic value they have. If we could make three-state devices economically, we would have computers based on trits.
It is easy to represent real-world quantities as strings of bits. Sound and images can easily be converted to bits. Strings of bits can be converted back to sound or images.
We call a unit of 8 bits a byte. This is a convention. The fundamental unit of data used by most computers is an integer multiple of bytes; e.g., 1 (8 bits), 2 (16 bits), 4 (32 bits), 8 (64 bits). The size of a computer word is usually an integer power of 2.
There is no reason why a computer word can’t be 33 bits wide, or 72 bits wide. It’s all a matter of custom and tradition.