The physical layer of our network stack model is the most complex of all. Its main focus is on moving ones and zeros from one end of the link to the next. The physical layer consists of devices and means of transmitting bits across computer networks. A bit is the smallest representation of data that a computer can understand. It's a one or a zero. These ones and zeros sends across networks at the lowest level are what make up the frames and packets of data. A standard copper network cable, once connected to devices on both ends, will carry a constant electrical charge. Ones and zeros are sent across those network cables through a process called modulation. Modulation is way of varying the voltage of this charge moving across the cable. When used for computer networks, this kind of modulation is more specifically known as line coding. It allows devices on either end of a link to understand that an electr...