The binary system is a method for working with numbers based on only two digits: 1 and 0 (binary is also known as “base two”). Binary numbers are the basis for computer storage. Input into the computer is changed into binary numbers that the computer can store and manipulate. A binary numbering system uses a series of 1’s and 0’s to represent any number. Non-numbers (such as the letter D) or characters (such as a question mark) are assigned an eight digit binary number so that they too can be represented within the computer.

Binary numbers can also represent decisions and results. For example, a yes (or true) will be represented by a 1, and a no (or false) can be represented by a 0. Each one of these single signals, 1 or 0, is called a *bit.*Using this method, the computer can compare two numbers and, if they are equal, make the result equal to 1. If they are not equal, the result would be 0. In addition, the computer can take further action based on this comparison. For example, if the result was true (1), a certain series of commands could be performed. If the result were false (0), a different set of commands could be performed.

The 1’s and 0’s of a computer’s binary system are represented by two electronic states: ON (high voltage electrical current) or OFF (low current). Quite simply, the 1’s and O’s are like little ON/OFF switches inside the computer. Basing an electronic system on the binary system that uses just two numbers is much easier and less expensive than using the decimal system (which has to differentiate between 10 different states: 0, 1,2,3,4,5,6,7,8, and 9).

Binary data is stored as bits, each bit equal to a 0 or a 1. Eight bits equal one byte of information (a single character, such as the letter S or the number 4). For example, the binary number for the letter A is 01000001.

For those who like number puzzles, this is from Steve; To make the conversion between binary and decimal, start at the right and multiply each digit by the next higher power of two, then add up all your answers. So, with 10101, the first digit equals 1 (1 times 1: 2 to the 0^{th} power is 1); the next digit is 0 (2^{1} equals 2, but 2 times 0 makes 0); the third digit equals 4 (1 x 2^{2}); the fourth digit is 0 again; and the 1 on the left equals 16 (1x 2^{4}). And 16 + 0 + 4 + 0 + 1 = 21. What fun.