Recognising USB types: from USB-A to USB-C

By Sanne, 9 October 2026

Look, there are five cables on my desk that look almost the same. One charges my laptop, one pulls photos off my old camera, and one cannot get my second screen working. You cannot tell from the plug.

So I go through the types one by one: how to recognise them, how they differ inside, what the markings next to a port mean, and why Europe chose USB-C.

Why the difference matters

You only notice when it goes wrong. A backup that takes an afternoon instead of ten minutes. A laptop that will not charge from your phone charger. A second screen that stays black even though the cable is plugged in.

Honestly, it is almost never the laptop. It is a port that does something other than you thought, or a cable that does less than the port. If you know what to look for, you buy the right cable and the right laptop first time.

The six plugs you will come across

The shape tells you which plug fits. Below I show them at the same scale, as you see them in a port, so you can also see the difference in size.

How the types differ inside

On the outside they differ in shape, inside in the number of wires. USB 2.0 has four: two for power and one pair for data. Over that single pair the data takes turns going back and forth, so sending and receiving at the same time is not possible.

USB 3 adds two pairs: one for sending and one for receiving, at the same time. That is why a fast USB-A has five extra contacts, and why an old USB-A plug still fits: the first four are in the same place.

USB-C has 24 contacts, mirrored, so the plug fits either way up. When you plug it in, a small contact called CC works out which way round it is, and over that same contact the devices agree on what they can do. That includes power: first 5 volts, then, if laptop, charger and cable can handle it, up to 20 volts and 5 amps, which is 100 watts. Since 2021, USB Power Delivery 3.1 goes up to 48 volts and 240 watts.

The same wires can also carry video. The laptop then switches some of the contacts to DisplayPort; that is called Alternate Mode. USB4 and Thunderbolt go a step further and send data, video and PCIe through one cable at the same time, which even allows an external graphics card.

How to tell what a port can do

With USB-A the colour still tells you something. With USB-C it does not: from the outside every port looks the same, and the manufacturer is supposed to state what each port can do. So look at the marking next to the port, and if in doubt at the specifications.

Speeds and names

Honestly, the names are a mess. USB 3.0, USB 3.1 Gen 1 and USB 3.2 Gen 1 are all three 5 Gbps. The organisation behind USB therefore recommends naming only the speed, such as USB 10Gbps. If you see an old name, look it up in this table.

The cable counts too

A port cannot do more than its cable. There are USB-C cables that are only USB 2.0: 480 Mbps at most and no video. On a fast port such a cable stays slow, and a second screen stays black.

Cables also differ in power. An ordinary USB-C cable is rated for 3 amps, which is 60 watts. For more, a chip in the plug tells the laptop what the cable can take; the heaviest cables go up to 240 watts. Certified cables carry a logo on the plug with the speed and the power, for example 40Gbps and 240W.

The European rule: one charger for everything

Since 28 December 2024, phones, tablets, cameras, headphones, speakers, e-readers, keyboards, mice and a few other devices placed on the EU market have to be able to charge via USB-C. For laptops this applies from 28 April 2026. It is set out in Directive (EU) 2022/2380, an amendment to the European rules on radio equipment.

What is required: a USB-C port for charging, USB Power Delivery as soon as a device charges faster than 15 watts, so any good charger works, the option to buy the device without a charger, and a pictogram and label saying whether a charger is included and how much power the device needs. There is no limit in watts: according to the European Commission’s guidance, a laptop that needs more than 100 watts is covered too.

The rule applies to devices placed on the EU market for the first time from that date. What was already on the EU market before may continue to be sold.

Why: according to the Commission’s 2021 proposal, discarded and unused chargers together account for about 11,000 tonnes of waste a year. Honestly, I think it is a good rule. One charger fewer in my bag, and no more drawer full of cables that fit nothing.

Examples: which laptop has which ports

A few business laptops, with what the manufacturer says about their ports. It shows how different two laptops with USB-C can be.

And with a docking station

There too, the difference is in the cable to the laptop. A USB-C dock such as the HP USB-C Dock G5 needs a USB-C port with video. A Thunderbolt dock such as the HP Thunderbolt Dock 120W G4 only reaches full speed on a Thunderbolt port, with more room for screens and fast storage.

A bit of history

Before USB, a computer had separate connections: a serial and a parallel port, and dedicated connections for keyboard, mouse and joystick. In January 1996 came USB 1.0, drawn up jointly by a group of computer companies, with one plug for everything and up to 12 Mbps.

USB 2.0 followed in April 2000 with 480 Mbps, and the same year the Mini-USB for small devices. In 2007 came Micro-USB, in 2008 USB 3.0 with 5 Gbps, in 2014 USB-C, the first plug that fits either way up, and in 2019 USB4.

And what is still to come

The next step is already here. USB4 Version 2.0 reaches 80 Gbps, and can tilt the split to 120 Gbps one way and 40 the other, useful for a high-resolution screen. Thunderbolt 5 reaches the same speeds, and charging goes up to 240 watts.

Europe is not done either. From 14 December 2028, chargers themselves must have at least one USB-C port. A European standard for wireless charging was requested in 2025, and every five years the Commission looks at which devices to add; the first report, from June 2026, names smartwatches, VR headsets and game controllers among others.

In short

The shape shows which plug fits, the marking next to the port what it can do: the trident with SS or a number with Gbps for fast data, a lightning bolt for Thunderbolt, the DisplayPort symbol for video and a battery for charging. USB-C is the plug of today and tomorrow, but check for every port and every cable what it really does. A laptop with two Thunderbolt ports and one or two USB-A ports has everything you need day to day.

Why refurbished at DSL Tech?

Every laptop at DSL Tech is checked on more than 30 points and comes with a 2-year warranty. Customers rate us 9.0 on average, you pay securely by iDEAL or in three instalments with in3, and order before 12:00 and your laptop arrives tomorrow.

Sources

• Directive (EU) 2022/2380 on a common charger (EUR-Lex)
• European Commission guidance on the common charger, C/2024/2997 (EUR-Lex)
• European Commission: One common charging solution for all
• USB-IF: consumer naming for USB speeds
• USB-IF: logos on USB-C cables
• USB-IF: USB 80Gbps announcement
• USB-IF: USB Power Delivery 3.1 up to 240 watts
• Intel: Thunderbolt 4 and USB-C