Many objects have two possible states: on or oﬀ, up or down, black or white, left or right. The electronic components of computers are the same and the entire working of the computer is based on this. We can represent one state by a ‘1’ and the other by a ‘0’. Combining several of these is how computers manipulate, store and transmit information. They read a number like ‘1001’ in the binary number system, rather than the usual decimal number system. Binary numbers are at the core of every computer and understanding how machines store and send information in this way is crucial to understanding how they work, and break!