The binary number system is a base 2 number system, just like common numbers are base 10. That is, the rightmost digit is the 20 place, the next is the 21 place, and so on, as shown in the table.
Use this binary to digital converter to see some conversions between the numbers you are used to and their binary equivalents. Type a number in either field and press the button next to it. Note that this converter doesn't work on negative numbers.
Binary number representation is an important step in getting machines to recognize code, since, as you'll see in Module 7, it's easy to make electronic circuits recognize when a voltage is ON or OFF, which is directly equivalent to binary counting.