Binary is a number system that is represented by only two digits, 0 and 1. It is the foundation of all computer operations, as computers use binary to process and store data. It is a "base-2" number system, rather than decimal. Each digit in a binary number is called a "bit", and combinations of bits represent different values and instructions. Typically, a "O" in binary means "OFF", "FALSE", or "NO". On the other hand, "1" means "ON", "TRUE", or "YES".
 

 
How to Read and Count in Binary
Binary is often put into groups of 8 bits, also known as “octets”.
Each bit in an octet represents a power of 2, starting with 1 and increasing from right to left.

The top row in the visual example is an octet, and the bottom row is what each bit represents in decimal form.
Knowing that the bits represent a positive value and a negative value, we can use this to read what the entire octet represents by adding what is “positive”, and ignoring what is “negative”.
 
Going by the above example:


11010101
128 + 64 + 16 + 4 + 1
(We didn’t include “32”, “8”, or “2” in the equation, since their place was marked with a “0” bit.)
Adding the decimal numbers together, we get a value of “213”.
 
So, “11010101” represents a decimal value of “213”.