What are bytes?

A byte is a very small amount of computer data. A 1000 bytes or a kilobyte is about the size of a thumbnailed picture.

Another answer:

A byte is combination of 8 bits. A bit can be either 0 or 1. This combination of 8 bits of either 0 or 1 make up the lowest form of all letters, characters. and numbers store in a computer. BTW, in some cases the byte can be broken up in to two 4 bit parts called a "nibble".