Hexadecimal is a number system that we use to represent the data in a computer in a technical way. There are lots of number systems in the world. Humans us the decimal number system and computers use the binary number system, but to make easier for humans we use a hexadecimal with computers.

The decimal number system is a base 10 number system is what most humans have always used. It has 10 single digit numbers which range from 0 thru 9. We probably started using it as we have 10 fingers and when we ran out of fingers counting we made a mark on the ground which would b the 10’s column. However it is not the only number system humans have used. The ancient Babylonians used a base 60 number system which has 60 single digit numbers. Thy also invented the clock and determined how many degrees are in a circle which is why those are numbers off 60 (60 minutes in an hour, 60 seconds in a minute, 360 degrees in a circle).

The computer uses a base two number system which is binary. It only has the single digit numbers 0 and 1. The computer uses this system as it is easy to store numbers in it easily as 0 or 1 can be represented as either on or off, a hole in a CD or not, a positive or negative electronic charge. The computer handles changing the binary ones and zeros to decimal numbers and letters automatically for us so you just see and use decimal numbers but what is actually in the computer is binary.

If you wanted to look to see what exactly was stored in the computer (computer people do this regularly to find out why a program quit working (crashed) or the data is coming out wrong or what is really going across a wire) then you can do a printout of the memory or disk and you would get thousands or more of zeros and ones. You would go crazy looking at a sheet full of zeros and ones and trying to find the set that represents the value you are looking for. (Basically it takes 8 binary numbers to store a single decimal number or a letter in a computer). However we can represent 4 binary numbers as a hexadecimal number so the list gets smaller and has a better variety of characters.

Hexadecimal is a base 16 number system, which means it has 16 single digit numbers. The single digit numbers are 0 thru 9 and the letters A thru F. We can represent a single hexadecimal number in 4 binary digits. The number F in hexadecimal is equivalent to 15 in decimal. You will see hexadecimal numbers used sometimes. As we move to IP version 6 you will see IP address (the address of your computer on the Internet expressed as a hexadecimal number. All devices that connect to the Internet have a MAC address (a fixed permanent address like your house number and street name) and it is always shown in hexadecimal. Look on the bottom of your Internet router/switch/modem and you will see the MAC address.

The good news is that we normally work in decimal with the computer like we are used to. The computer works internally in binary and only times we worry about hexadecimal (sometimes called hex) and binary is when something goes wrong.