what is a byte ?

A byte is 8 bits ,

 [_ _ _ _ _ _ _ _ ]
  7 6 5 4 3 2 1 0 

number of bits = 7 - 0 + 1 = 8

A bit can have a value of 1 or 0 .

The min value of a byte is when all the bits are 0 :

[00000000]
 76543210

and it is equal to zero.

The max value of a byte is when all the bits are equal to 1 .

[11111111]
 76543210

and it is 255.

Byte representation in decimal

A byte is 8 bits , and it is represented in binary . We can convert it to decimal by multiplying each bit by two to the power of the position of this bit , and summing the result . The min value of a byte in decimal is 0 , and its max value is 255 .

Byte representation in hexadecimal : base 16

Instead of writing a byte using its binary representation , we can write a byte using its hexadecimal representation . In hexadecimal , each 4 bits are grouped into one character , which can be between [0-F]

Hence we can write a byte by using only two hexadecimal [ 0- F] characters .

Byte representation in octal : base 8

We can also write a byte by using the octal notation . In octal , each 3 bits are grouped into one character , which can be between [0-7] .

A byte is formed of 8 bits . This means , that we must use 3 octal [0-7] digits , to represent a byte . The leading octal digit must have a max value of 3.

Summary

[
byte        : 8 bits   , 
represented : binary   , decimal , octal , hexadecimal
min         : 00000000 ,   0     ,  000  ,    00 
max         : 11111111 ,  255    ,  377  ,    FF
]