Connections & cables
There are effectively two ways devices can be connected: wirelessly, or by cable. Each has different characteristics of capacity (what kind of data can be sent, and how fast) and range (over what physical distance). This page is about the cables that join devices.
You can usually identify a cable’s type by looking at the physical connector on the end, or the shape of the hole of the socket it plugs into. Some cables only fit one way up, so you must look at the socket to see which way round they need to be.
If the sockets or connections available to you don’t match, you might be able to use an adaptor.
Cables that join your computer to a monitor are often called video cables.
These are some of the more common types:
Ethernet
Sometimes simply called a network cable. Connects your computer to a network
(typically the cable goes to a router) if, for example, you don’t have WiFi.
The clip on the top snaps into the socket to stop it getting pulled out. The
clip is fragile, so is sometimes protected by a flexible sheath to prevent it
snapping off.
USB A
Connects your computer to another device with
USB.
This was the first of the USB connectors to be introduced and is still widely
used.
Micro USB
Connects your computer to another device with
USB.
Mini USB
Connects your computer to another device with
USB. These were mostly used on small devices
like cameras and phones.
USB 3
Also called SuperSpeed USB. It physically
fits in the earlier USB A — the blue indicates that data speed/protocols are
different.
USB B
Connects your computer to another device with
USB.
USB C
Connects your computer to another device with USB. Also used to supply power (connected to a power supply or
charging port). Thunderbolt 3 and 4 interfaces use this USB C connection
too, although their technical capablities (such as the speed they can transmit
data) are different.
Lightning
Connects some Apple devices to a power supply for charging. When used with
a dongle this can also transfer data.
HDMI
High-Definition Multimedia Interface
Connects your computer to a
monitor.
DVI
Digital Visual Interface
Connects your computer to a
monitor.
DVI connections often have stalks you can twiddle so you can tighten the
connection.
DisplayPort (DP)
Connects your computer to a
monitor. DP can be used by other
devices too, such as external storage,
if they support the Thunderbolt protocol.
Mini DisplayPort
Connects your computer to a
monitor. On Apple computers, may also
be used to connect to other kinds of device using the Thunderbolt (1 or 2)
interface.
VGA
Video Graphics Array
Connects your computer to a
monitor.
VGA is mostly found on old devices, and the cable uses a D-shaped connector
with 15 pins or holes (“D-15”). Like other D connectors, the stalks are
threaded so you can tighten the connection.
Serial port
Connects your computer to a serial port for sending one character at a time,
which is used for low-level communication between machines. You don’t find
these on consumer-level devices any more but you might still use them in labs
or robotics applications. The stalks on these D connectors are threaded so you
can twiddle them to protect the pins from bending and to tighten the connection.
Coaxial (“coax”) cable
Used as a transmission line, often for networks. Comprised of two conductors:
the inner — which runs through the middle — and, separated by an insulator, the
outer sheath around it. The two conductors share the central axis, hence
“coaxial”. If your internet (or TV) comes into your house through a cable (not
fibre), it’s probably one of these.
Caring for cables
Don’t stretch cables, crush them, or bend them sharply. The wire inside cables is ductile, but can be broken if it gets folded too acutely. If you see a knot has formed in a cable, gently untangle it before it gets pulled tight.
The pins in the connectors are delicate electrical contacts. If you can’t get a connector into a socket, never force it. Instead, check that:
- The connector and socket do match.
- You have them right way up.
- There’s nothing in the socket that’s getting in the way.
What about optical fibres?
Fast network connections are often implemented by transmitting light along optical fibres (instead of electric signals over along wires). It’s rare for this to be a connection on your own computer, unless your computer is a server. Fibre optic cables carry data at the speed of light for hundreds of miles and are used in subsea cables to connect continents. But metal wires are cheaper and more robust than fibres, which is why they are used for the local connections you might be plugging in and out.