An Ethernet port (aka jack or socket) is an opening on computer network equipment that Ethernet cables plug into. Their purpose is to connect wired network hardware in a local area network (LAN), metropolitan area network (MAN), or wide area network (WAN).
You might see an Ethernet port on the back of your computer or laptop. A router usually has several Ethernet ports to accommodate multiple wired devices on a network.
An Ethernet port accepts a cable that has an RJ-45 connector. The alternative to using such a cable with an Ethernet port is Wi-Fi, which eliminates the need for both the cable and its port.
What Ethernet Ports Look Like
An Ethernet port is a little wider than a phone jack. Because of this, it’s impossible to neatly fit an Ethernet cable into a phone jack, which makes it a little easier when you’re plugging cables in – you can’t really plug it into the wrong port.
The picture at the top of this article is a really good demonstration of what an Ethernet port looks like. It’s a square with a couple rigid areas at the bottom. As you can also see in the picture, the yellow Ethernet cable is built the same way.
Ethernet Ports on Computers
Most desktop computers include one built-in Ethernet port for connecting the device to a wired network.
A computer’s built-in Ethernet port is connected to its internal Ethernet network adapter, which is attached to the motherboard.
Laptops usually have an Ethernet port too, so that you can hook it up to a network that doesn’t have wireless capabilities. A notable exception is the MacBook Air, which doesn’t have an Ethernet port but does support connecting an Ethernet dongle to its USB port.
Tip: If you have internet connectivity issues, the Ethernet port is probably the first place you should look because the cable might be unplugged. This is especially the case if the computer or laptop was recently moved, which can easily knock the cable out of the Ethernet port.
Ethernet Ports on Routers
All popular broadband routers feature Ethernet ports, and usually a few of them. This is how multiple wired computers in a network can reach the internet and the other connected devices on the network.
An uplink port (also called WAN port) is a special Ethernet jack on routers that’s used specifically for connecting to a broadband modem. Wireless routers include a WAN port and typically four additional Ethernet ports for wired connections.
Ethernet Ports on Consumer Electronics
Many other types of consumer gadgets now also include Ethernet ports for home networking, like video game consoles, digital video recorders, and even some newer televisions.
Another example is Google’s Chromecast, for which you can buy an Ethernet adapter so that you can use your Chromecast without Wi-Fi.