Ethernet was created at Xerox PARC by Bob MetCalfe in the early 1970s. The idea at the time was to be able to exchange information between computers within the same building, which was called a local area network (LAN).

The name "Ethernet" comes from the simple system explained below. That line is "Ether" - the medium that early physics thought filled the universe and that allowed the transmission of light.

At first, Ethernet used a simple coaxial cable to connect all computers together. Everyone can transmit information (aka Ethernet frames) over the wire at any time. All other computers on the line will listen to these frames and choose the ones destined for them. It's a very simple system that requires minimal wiring, but at a cost: two computers can start transmitting at the same time, making frames mixed and garbled. To avoid this, Ethernet uses a special algorithm called "CSMA/CD" ("Carrier Sense Multiple Access with Collision Detection").

Basically, the protocol makes sure the line is not in use before sending any frames. This was a major feature of Ethernet's early years and gave it an unfair reputation as an unpredictable and unreliable networking technology.

As Ethernet evolved, it lost the need for the shared medium. Since the introduction of Ethernet switches in the mid-1990s, Ethernet is characterized by a star topology, where each computer has its own dedicated line, connected to an Ethernet switch, which receives and relays frames destined to the other computers in the network.

This development made Ethernet truly "plug and play" and gave it a huge price and performance advantage over any other competing networking technology.

The IEEE 802.3 working group approved the first Ethernet standard in 1983. Since then, the technology has continued to evolve and embrace new media, higher transmission speeds, and changes in frame content.

Here are some of the changes:

• 802.3ac was introduced to accommodate VLAN and priority tagging.

• 802.3af defines Power over Ethernet (PoE), which is crucial to most Wi-Fi and Internet Protocol (IP) telephony deployments.

• 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, and 802.11ax define the equivalent of Ethernet for WLANs.

• 802.3u ushered in 100BASE-T -- also known as Fast Ethernet -- with data transmission speeds of up to 100 Mbps. The term BASE-T indicates the use of twisted-pair cabling.

Today, when people talk about Ethernet, they can be referring to either of two things: (a) the basic Ethernet technology, in the form of a switch that can be used to connect computers, or (b) the Ethernet frame format, which is used to encode the messages that are transmitted over the network.

The Ethernet frame format is used by several different technologies, some completely unrelated to the original Ethernet standard. It allows different devices to connect to an Ethernet network. Some examples are WiFi and WiMAX standards, but also proprietary radio and SDH transmission systems. Over the years, Ethernet has also gained many features, including advanced management options (the Ethernet OAM standard), enabling it to be used in professional telecom applications.

Ethernet is now used everywhere. It is a tremendous success.

What makes Ethernet so popular?

The key reason for its success over competing technologies such as IBM's token ring was its inexpensive price tag. As network technology advanced, Ethernet's ability to evolve and deliver higher levels of performance, ensured its sustained popularity.

The star topology was the main enabler. Communication became possible (albeit over shorter distances of up to 100 m), using cheap, dedicated, “twisted-pair” copper wiring, as compared to the far more expensive coaxial cables required by competing LAN technologies (and by Ethernet itself originally). 

Originally, it was a Thicknet RG-8 with "vampire transceivers," which penetrated the shield and connected the electronics to the core wire without causing a break in the cable. 

That eventually evolved into RG-58 "Thinnet", RJ-45 twisted pair networking which you may be familiar with today, and fiber optic-based solutions.

Just to clarify, coax is abandoned because it’s heavy, difficult to work with, not very flexible, and also expensive.

Note that two twisted pairs per connection were used for point-to-point communication: one for receive and one for transmit. Therefore, sending and receiving can now happen at the same time.

Data transfers were unidirectional: Each pair worked in only one direction. Later, to achieve speeds of 1000Mbps, the electronics were made smart enough to ensure bidirectional communication over a single twisted pair by using hybrid circuits.

Anyway, you can’t talk about Ethernet without talking about cables, since Ethernet is designed for wired networking. Let’s meet our best partners now - twisted pair.

Types of Ethernet cables

Twisted-pair cables for Ethernet are inexpensive to deploy and are fairly flexible, meaning they can snake around corners, inside walls, ceilings, or just about anywhere else to connect servers, routers, hubs, devices, and terminals.

In a rather neat move, most companies that manufacture Ethernet cables decided long ago to ditch the standard gray scheme and release them in a rainbow of colors. In addition to beautifying computer rooms and data centers, this color coding allows IT technicians to visually group their network connections into groups for quick troubleshooting.

The standard plugs on both ends of the twisted pair are very similar to the same kind of connections used by wired telephone systems. Most of the time, simply plugging in the device and connecting it to the network using one of these cables is the only step to getting an instant connection. All of the backend routings of packets and data are then handled by Ethernet and other advanced protocols like Spanning Tree.

The longtime standard for Ethernet cables is called Category 5, commonly known as Cat 5. The Cat 5 standard has been in use since 2001. Cat5 cables support 100BASE-T Ethernet. 100 means speeds up to 100 Mbps. While the main function of the cables is to support Ethernet networking, they also work with many telephone and video applications.

A slightly more advanced cable called Category 5e is also used today for faster Ethernet applications. Category 5e cables are aimed at 100Mbps Ethernet, but their design also lets them support higher speeds like Gigabit Ethernet, while Cat 6 works with 10 Gigabit.

There are also Ethernet crossover cables that connect two devices of the same type. These cables enable two computers to be connected without a switch or router between them.

Will Ethernet’s popularity continue?

The simplicity of the Ethernet standard and the ability to support faster speeds while maintaining backward compatibility has allowed the protocol to evolve with many technological advancements. 

When you compare Cat6’s raw speed of 1Gbps to the original 10 Mbps standard supported by early Ethernet, it's easy to see how far the protocol has come.

The IEEE Ethernet Working Group ratified the specifications for 200 Gbps and 400 Gbps Ethernet several years ago.

Technically, a specification for 800 Gbps Ethernet also exists, but no one is currently using it outside of test environments. What's interesting about Ethernet is that because it's such an open protocol, there's no reason to think that even 800 Gbps is anywhere near the theoretical maximum.

Seems like these super high speeds are unnecessary, for now, they probably are. But the volume of data has been growing, as has the number of users and devices connected to the Internet. In the not-too-distant future, speeds that seem unnecessary today may soon become commonplace, or even a requirement.

So, what are your thoughts on Ethernet now?