In the electronic world, it is the transfer of data and information from one location to another. "Data communications" or "datacom" refers to digital transmission. "Telecommunications" or "telecom" refers to a mix of voice and data, both analog and digital. However, due to digital convergence, "telecommunications" implies "data communications."
"Networking" generally refers to a local area network (LAN), but it may refer to a private wide area network (WAN) or to the public Internet.
"Communications" may refer only to voice-related subjects such as PBXs, modems, call centers and the like or to any form of data transfer.
The way data communications systems "talk to" each other is defined in a set of standards called "protocols." Protocols work in a hierarchy starting at the top with the user's program and ending at the bottom with the plugs, sockets and electrical signals. See communications protocol
and OSI model
Analog vs. Digital Communications
Prior to the Internet, the world's largest communications system was the telephone network, a mix of analog and digital lines. It used to be entirely analog and transmitted only voice frequencies. Today, the only analog part is the line between the telephone and a digital conversion point (digital loop carrier) within about a mile of the customer.
Amplifiers Boost the Noise
Analog systems are error prone because the electronic transmission of sound waves gets mixed together with unwanted, nearby signals (noise). In long distance analog telephone networks, amplifiers were placed in the line every few miles to boost the signal, but they also boosted the noise. By the time the person or modem received the signal at the other end, it may have been impossible to decipher.
In a digital telephone network, the transmitted voice is binary. Instead of amplifiers, repeaters analyze the incoming signal and regenerate a new outgoing signal, and any noise on the line is filtered out. When data are made up of only 0s and 1s, they can be easily distinguished from the garble. Digital is simple.
The First Analog Communications
In 1876, Alexander Graham Bell sent the first electronic communications over a wire when he said, "Mr. Watson. Come here! I want you!" (Image courtesy of AT&T.)