In a digital system, only two specific voltage levels are considered: A High voltage and a Low voltage. In an analogue system again, all the possible values between these two limits are also considered. A digital result can be compared with a light being switched ON or OFF, while the analogue equivalent is a light being controlled by a dimmer switch. Typical digital voltages are 5 volt for High and 0 volt for Low or ground.
In place of using words such as ON or OFF, or “at 5 volt” and “at ground” potential, a shorter format is to use 1 or 0. A 1 will indicate a 5 volt or ON level, while a 0 is used for ground or OFF. When a setting is switched to 1, it will be referred to as to SET the value, and when it is switched to 0, it will be called to RESET or to CLEAR the value.
Such a single setting of either 1 or 0 is the smallest unit of information storage, and is called a bit. When two or more of these 1 and 0 bit values are grouped together in a specific order, the right-hand bit is called the Least Significant Bit or LSB. The left-hand bit is the Most Significant Bit, or MSB.