What is Ethernet?

Ethernet is the wired networking standard that has connected computers, routers, switches, and other devices since the 1980s. While WiFi gets more attention today, Ethernet remains the backbone of virtually every network on the planet. The cables running between your router, modem, and wall jacks are Ethernet. The connections inside data centres, offices, and server rooms are Ethernet. It is the most reliable way to move data across a local network.

The technology was originally developed at Xerox PARC in 1973 and later standardised as IEEE 802.3. Over the decades, Ethernet has evolved from 10 Mbps shared coaxial cables to 10 Gbps (and beyond) dedicated twisted-pair and fibre connections. Through all of these changes, the fundamental principle stayed the same: a direct, physical connection between two network devices.

How Ethernet Works

Ethernet transmits data as electrical signals over copper cables (or as light pulses over fibre optic cables). Each device on the network has a unique MAC address burned into its network interface, and Ethernet frames carry data from one MAC address to another.

When your computer sends data to your router, it packages the information into Ethernet frames. Each frame contains the source MAC address, the destination MAC address, the payload (the actual data), and an error-checking value called a Frame Check Sequence (FCS). The receiving device checks the FCS to verify the data arrived intact.

Modern Ethernet networks use a star topology. Every device connects to a central switch or router rather than sharing a single cable. This means each connection gets dedicated bandwidth. When your desktop sends data to the router, it does not compete with your NAS drive doing the same thing on a different port. Each port on a switch or router operates independently.

Full-duplex communication allows Ethernet devices to send and receive data simultaneously. WiFi, by contrast, operates in half-duplex mode at the physical layer, meaning devices must take turns transmitting. This fundamental difference is a major reason why Ethernet delivers more consistent performance.

Ethernet Cable Categories

Ethernet cables come in different categories, each with different speed and distance ratings. The category number is printed on the cable jacket. Choosing the right cable matters because your connection speed is limited by the weakest component in the chain.

Cat5e (Category 5 Enhanced) supports speeds up to 1 Gbps at distances up to 100 metres. It was the standard for home networking for over a decade. Cat5e is still perfectly adequate for gigabit internet connections, which most households have. The cables are thin, flexible, and inexpensive.

Cat6 steps up to support 10 Gbps at distances up to 55 metres, and 1 Gbps at the full 100-metre maximum. Cat6 cables have tighter twisting and often include a plastic spline separator between the wire pairs to reduce crosstalk. For new installations, Cat6 is the recommended choice because it provides headroom for future speed upgrades at only a modest price increase over Cat5e.

Cat6a (Category 6 Augmented) supports 10 Gbps at the full 100-metre distance. The cables are thicker and stiffer than Cat6, with additional shielding to eliminate alien crosstalk between adjacent cables. Cat6a is the standard for professional installations and is worth considering if you are running cables through walls during a renovation and want them to last 15 or more years.

Cat7 and Cat8 exist but are rarely relevant for home users. Cat7 uses non-standard connectors (GG45 or TERA instead of RJ45), and Cat8 is designed for short-run data centre connections at 25-40 Gbps. If someone is selling you “Cat7 with RJ45 connectors,” you are functionally getting Cat6a performance.

The RJ45 Connector

Every Ethernet cable terminates in an RJ45 connector, the clear plastic plug that clicks into the port on your router, switch, or computer. RJ45 stands for Registered Jack 45, and it contains eight metal contacts that correspond to the eight wires inside a standard Ethernet cable.

The connector has a small plastic tab that locks it into the port. Pressing the tab releases the cable. These tabs break frequently over time, which is the number one reason Ethernet cables stop staying connected. If a cable keeps falling out of the port, replacing it is usually cheaper and faster than trying to fix the tab.

Inside the connector, the eight wires follow a specific colour-coded wiring pattern. The two most common standards are T568A and T568B. For home networking, it does not matter which you use as long as both ends of the cable match. Pre-made cables from stores use T568B almost universally.

When Ethernet Beats WiFi

Ethernet outperforms WiFi in every measurable networking metric except convenience. Understanding when to use each helps you build a better home network.

Latency is where Ethernet dominates most decisively. A wired connection typically adds less than 1 millisecond of delay. WiFi adds 5 to 20 milliseconds under good conditions and can spike to 50 ms or more during congestion. For online gaming, video calls, and real-time applications, this difference is immediately noticeable.

Consistency is the other major advantage. WiFi speeds fluctuate constantly based on interference, distance, and competing devices. Ethernet speeds stay flat at the rated speed of the slowest link in the chain. If your router has a gigabit Ethernet port and your computer does too, you get a full gigabit, all the time.

Security is inherently stronger on a wired connection. Someone would need physical access to your cable or switch to intercept Ethernet traffic. WiFi signals travel through walls and can be captured by anyone within range, making encryption essential. Ethernet does not require encryption for local traffic, though it is still wise for sensitive data.

Reliability matters for devices that cannot tolerate dropouts. A wired NAS (network-attached storage), a home security system, or a VPN gateway should never depend on a wireless connection that might hiccup during a firmware update or microwave interference.

Setting Up Ethernet at Home

The simplest Ethernet setup requires nothing more than a cable and two devices with Ethernet ports. Plug one end into your router’s LAN port and the other into your computer’s Ethernet jack. The connection establishes itself automatically.

For connecting more devices than your router has ports, add an unmanaged Ethernet switch. A five-port or eight-port gigabit switch costs very little and simply plugs into one of your router’s LAN ports. Every device connected to that switch can communicate with the rest of the network at full speed.

Running Ethernet cables through walls is the cleanest approach for permanent installations. You will need a drill, cable clips or conduit, a punch-down tool for wall plates, and Cat6 cable sold in bulk spools. Terminate each end at a keystone jack mounted in a wall plate. This gives your home a wired infrastructure that will outlast multiple generations of routers and devices.

For situations where running cables is impractical, powerline adapters and MoCA adapters offer alternatives. Powerline adapters send Ethernet data over your home’s existing electrical wiring. MoCA adapters use coaxial cable. Neither matches the performance of a direct Ethernet run, but both are significantly better than WiFi for stationary devices in hard-to-reach rooms.

Ethernet Speed and Your Internet Plan

Your Ethernet connection speed and your internet speed are two different things. Ethernet refers to the local connection between your device and the default gateway (your router). Internet speed refers to the connection between your router and your ISP.

If you have a 300 Mbps internet plan but a gigabit Ethernet cable to your PC, your internet downloads will max out at 300 Mbps. However, local network transfers (like copying files from a NAS to your PC) can use the full gigabit. Similarly, if your internet plan offers 2 Gbps but your Ethernet is only gigabit, the cable becomes the bottleneck for internet traffic.

For most homes with internet plans under 1 Gbps, Cat5e or Cat6 at gigabit speeds is more than sufficient. Homes with multi-gig internet plans (2.5 Gbps or 5 Gbps offerings from fibre ISPs) need Cat6 or Cat6a cables and devices with 2.5GbE or faster network interfaces to take full advantage.