Technology planning
How does the information in cables and wires get through to the other end of the cable? How does it know what to do when it gets there?
The information is encoded as digits (called "bits") in the binary (base-2) number system, which we write on paper as "1" and "0". Each bit is transmitted from one end of the cable to the other as an electrical signal. There are many ways these bits are transmitted, and the devices at each end of the cable must both use the same way. For example, inside your computer most information is encoded as +5 volts DC for a "1" and -5 volts DC for a "0" (5 volts is what you get from just a few AA batteries). The cables carry the electrical signals just like the power cable on an electric light does, using chemical properties of the metal (usually copper) in the cable. When the information gets to the other end of the cable, it is reconstructed back into bits by the receiving device. The device is usually part of a computer, and the computer looks for specific patterns in the bits to decide what to do with the information. Some computers always have programs running that are waiting for information (like web servers on the Internet), others will start a program to process the information when it arrives.