Hexadecimal

From Linux 101, The beginner's guide to all things Linux.

Hexadecimal, or hex, is a shorthand representation of binary. Although computers do not use it natively, it is often easier on humans to read hexadecimal instead of a much longer chain of binary.

Often times before a hexadecimal number a 0x is placed to indicate it as hexadecimal.

Hex is base 16 in the number system. Because of this, we need 16 symbols to represent the digits. 0 to 9 are obvious candidates, but because that is only 10 symbols, we need an additional 6. We take these from the beginning of the alphabet, so our actual symbol list is 0123456789ABCDEF.

Decimal value	Binary value	Hexadecimal value
0	0000	0x0
1	0001	0x1
2	0010	0x2
3	0011	0x3
4	0100	0x4
5	0101	0x5
6	0110	0x6
7	0111	0x7
8	1000	0x8
9	1001	0x9
10	1010	0xA
11	1011	0xB
12	1100	0xC
13	1101	0xD
14	1110	0xE
15	1111	0xF

The conversion table above shows how to convert from three important bases to one another. The important thing to note is that each hex digit represents 4 binary digits. This makes conversion between the two extremely easy: break any binary digit into groups of four, then use the table above to convert.

Example #1:
1101 1110 1010 1101 1011 1110 1110 1111 -> 0xDEADBEEF
0xD  0xE  0xA  0xD  0xB  0xE  0xE  0xF

Example #2: 
0xDECAFBAD -> 1101 1110 1100 1010 1111 1110 1010 1101

The above were good examples of how in some instances you can use hex to spell words, but that is rarely the case in terms of computers.