Bird watchers carry a field guide: a description of each species, where it’s found and what it’s commonly mistaken for. The edges of a laptop deserve the same treatment. Here’s every port you’re likely to meet, how to recognize it and what it’s actually good for.
USB-A
Looks like: a flat rectangle about half an inch wide. It only goes in one way up, which you’ll discover on the second try.
Does: connects the things most people already own, such as mice, keyboards, flash drives, printers and wireless receivers.
Spotting notes: a blue plastic tab inside usually means a faster port, and black usually means the older, slower USB 2.0. A small lightning bolt or battery symbol means it can charge a phone while the laptop sleeps.
Status: slowly disappearing from thin laptops, but still very useful. One or two is worth having.
USB-C
Looks like: a small oval with rounded ends. It goes in either way up.
Does: that depends entirely on the port, and this is the most important thing in this guide. USB-C is a shape, not a promise. Two ports that look identical may do very different things.
- Data only: moves files, and nothing else.
- Data and charging: can also power the laptop, usually labeled Power Delivery or PD.
- Data, charging and video: can run a monitor too, usually labeled DisplayPort or DP Alt Mode.
Spotting notes: look for tiny symbols beside the port. A plug or battery icon means charging. A small D-shaped display icon means video. No symbols at all often means data only. The spec sheet is the reliable source.
Commonly mistaken for: Thunderbolt, which uses the same connector.
Thunderbolt and USB4
Looks like: a USB-C port, with a small lightning bolt next to it for Thunderbolt.
Does: everything. Very fast file transfers, one or two high-resolution monitors, charging and docking stations, all through one cable. USB4 is a closely related standard with similar abilities, common on laptops with AMD processors.
Who needs it: anyone who wants to plug in one cable at a desk and have a monitor, keyboard, storage and power all connect at once. Also video editors who use fast external drives.
Status: standard on most mid-range and premium laptops. If you plan to use a dock, this is the port to look for.
HDMI
Looks like: a wide, flat port with two angled corners at the bottom.
Does: sends picture and sound to TVs, monitors and projectors. It’s still the easiest way to connect to a meeting room screen or a hotel television.
Spotting notes: the version matters. HDMI 1.4 runs a 4K screen at only 30Hz, which feels choppy. HDMI 2.0 does 4K at 60Hz. HDMI 2.1 goes higher, which matters for gaming monitors and TVs.
Commonly mistaken for: DisplayPort, which looks similar but has only one angled corner.
DisplayPort
Looks like: like HDMI with one corner cut off and three square ones. A smaller version, Mini DisplayPort, appears on some gaming laptops.
Does: connects to monitors, especially high refresh rate gaming ones.
Status: uncommon as a separate port on laptops now, since USB-C and Thunderbolt carry the same signal.
Headphone jack
Looks like: a small round hole, 3.5mm across.
Does: takes wired headphones and headsets. Most laptop jacks are “combo” jacks that handle a headset’s microphone as well.
Status: still on nearly every laptop, unlike phones. It never needs charging or pairing.
SD and microSD card readers
Looks like: a thin slot, about an inch wide for full-size SD and half that for microSD.
Does: reads memory cards from cameras, drones and action cameras.
Who needs it: photographers and video makers. A full-size SD slot is a real convenience for them. Others may never use it.
Spotting notes: some budget listings call a microSD slot “expandable storage”. It works, but card storage is slow, so it’s fine for photos and poor for programs.
Ethernet
Looks like: a squarish port, like a wider phone socket, sometimes with a hinged lower jaw on thin laptops.
Does: connects straight to a router by cable. It’s faster and steadier than Wi-Fi.
Who needs it: online gamers, people who upload large files and anyone whose Wi-Fi is unreliable. It’s common on gaming and business laptops and rare on thin ones. A USB adapter adds one cheaply.
Charging port
Looks like: a small round socket, or a slim rectangular one on some brands. Many laptops have dropped it and charge through USB-C instead.
Spotting notes: powerful gaming laptops still use their own charger, because they need more power than a typical USB-C charger supplies. If a laptop charges by USB-C, you can share one charger between it and your phone.
Security lock slot
Looks like: a tiny rounded rectangle, often with a padlock icon.
Does: takes a cable lock to tether the laptop to a desk. Useful in offices, libraries and shared rooms.
How many ports do you need?
A sensible everyday set looks like this.
- Two USB-C ports, with at least one that handles charging and video.
- One or two USB-A ports for older accessories.
- HDMI, if you ever present or connect to a TV.
- A headphone jack.
If the laptop you love falls short, a small USB-C hub fills the gaps at little cost. Hubs can only pass along what the laptop’s port supports, though. A hub plugged into a data-only port won’t run a monitor.
The one thing to remember
The shape of a port tells you what fits. It doesn’t tell you what works. Check the spec sheet for the words “Power Delivery” and “DisplayPort” next to any USB-C port before you count on it for charging or a monitor. Our guide to reading a spec sheet shows where to look, and how to choose a monitor covers the other end of the cable.
More reading: all Dealmania articles