Types of USB: Connectors and Speeds Explained (USB-C, USB4)

Open the drawer where you keep your cables and count the USB-C ones. If you are like most people, you have half a dozen, they all look identical, and at least one of them refuses to do the job you bought it for. One charges a phone in forty minutes. Another takes all night. A third drives a monitor without complaining. You have no reliable way to tell them apart until you plug each one in and find out the hard way.

We call the cable USB, the port USB, the flash drive USB and the speed USB, when those are four different things. Then the industry renamed the same product three times over, so even the people who work with it have to check a table now and then.

Here is the split almost nobody makes. One question is the shape of the connector (A, C, micro and the rest). The other is the standard for speed and power (USB 2.0, 3.2, USB4). The same USB-C connector can crawl at 480 Mbps or fly at 40 Gbps. It can carry power, data and video, or do nothing but charge. The shape tells you none of that. Hold the two questions apart and most of the frustration goes away.

What USB is and where it came from

USB stands for Universal Serial Bus, a standard for connecting peripherals, moving data and powering devices. Seven companies designed it in the mid-1990s: Intel, IBM, Compaq, Microsoft, NEC, Nortel and Digital. Their goal was blunt. Every computer of that era carried a museum of different sockets on the back, serial, parallel and PS/2, and nobody could agree on which cable went where. USB was the attempt to end that.

The first version, USB 1.0, landed in 1996. It was good for mice and keyboards, and little else. From there the specification kept growing until it became the universal plug you now take for granted.

Out of that effort came the USB Implementers Forum (USB-IF), the non-profit organisation that maintains the specification and certifies products today. It is the reference you want when a port, a cable or a charger has to deliver what its packaging promises.

How the standard evolved: from USB 1.0 to USB4

Every generation multiplied the speed of the one before it, and that is the root of the naming mess. This is the path, with the official figures the USB-IF publishes:

• USB 1.0 and 1.1 (1996-1998): two speeds, Low Speed at 1.5 Mbps and Full Speed at 12 Mbps. Enough for keyboards, mice and simple printers.
• USB 2.0 (2000): introduces High Speed, 480 Mbps. The jump that made moving files and connecting external drives practical.
• USB 3.x (2008-2017): the SuperSpeed family adds lanes: 5 Gbps in USB 3.0, 10 Gbps in USB 3.1 and 20 Gbps in USB 3.2 with two lanes at once.
• USB4 (2019): up to 40 Gbps over the USB-C connector, built on the Thunderbolt 3 protocol Intel contributed to the standard. It shares bandwidth between data and video dynamically.
• USB4 v2 (2022): pushes to 80 Gbps and allows an asymmetric mode of up to 120 Gbps when a display needs more throughput than the data.

The takeaway you want to keep: speed does not travel in the marketing name. A USB-C port can hide any of these generations behind it, so the version is something you check against what the host controller supports and what the cable can handle.

Types of USB by speed (the standard)

When people say the «type» of USB in the technical sense, they mean speed. And this is where the famous mess lives: the same speed has collected up to three labels depending on which revision of the specification you read.

Current name	Older names	Speed	In practice
USB 2.0	High Speed	480 Mbps	Mice, keyboards, simple peripherals
USB 5 Gbps	USB 3.0 / 3.1 Gen 1 / 3.2 Gen 1	5 Gbps	Basic external drives, flash drives
USB 10 Gbps	USB 3.1 Gen 2 / 3.2 Gen 2	10 Gbps	Fast drives, capture cards
USB 20 Gbps	USB 3.2 Gen 2×2	20 Gbps	External SSDs, large copies
USB4	None	40 Gbps	Ultra-fast SSDs, monitors, docks
USB4 v2	None	80 Gbps	The newest, still rare

USB 2.0 remains the workhorse for simple things, and that is fine. A keyboard does not need 10 Gbps. Speed starts to matter with drives, video and docks.

One row deserves a note. The 20 Gbps of USB 3.2 Gen 2×2 come from two separate 10 Gbps lanes running at the same time. That is why the mode almost never appears on a classic USB-A connector and stays reserved for USB-C, which carries the pins it needs.

What they’re called today: speed-based naming

Faced with the «Gen» disaster, the USB-IF reordered the vocabulary so the name says what matters. Where you used to read USB 3.2 Gen 2×2, you now see USB 20 Gbps. Where you used to read USB4, you sometimes see USB 40 Gbps. The label changed. The technology underneath did not. That is why both vocabularies keep sitting side by side on boxes and product pages.

When you are stuck between an old label and a new one, translate everything to gigabits per second. That number is what you will actually notice when you copy a large file or push video to a monitor.

Connector types: A, B, micro and USB-C

This is the part most people mean by «types of USB»: the physical shape.

Connector	Look	Where you find it
USB-A	Rectangular and flat, non-reversible	The classic port on PCs and older chargers
USB-B	Square and wide	Printers, scanners
Mini-USB	Trapezoidal, 5 or 8 pins	Older cameras and gadgets
Micro-USB	Very flat and small	Phones from a few years ago, controllers, power banks
USB-C	Oval and reversible	Almost everything modern

USB-A is the one you always plug in upside down on the first try, and on the second. Micro-USB ruled phones until its natural successor arrived, the USB-C. USB-B still shows up on printers and lab gear, and mini-USB belongs in a museum unless the kit you own has seen a couple of decades.

The shape guarantees nothing else either. One USB-A can run at 480 Mbps and another at 5 Gbps depending on the port, and a USB-C can be charge-only. The label on the port, when there is one, is the only reliable clue.

USB-C: one connector, a thousand possibilities

This is the most expensive misunderstanding in the industry. USB-C is a connector, not a speed standard. Two cables with the same shape can be radically different inside:

• One runs at 480 Mbps (USB 2.0) and another at 40 Gbps (USB4). Nothing about the outside warns you.
• One charges and nothing more. Cheap charger cables are usually exactly that.
• Power varies too. A basic charger pushes 7.5 W. The newest USB Power Delivery allows 240 W.
• Video is optional. Some cables carry DisplayPort or HDMI in alternate mode, and some carry no video at all.

That is why the same USB-C port can charge a laptop, drive a monitor and connect an SSD, and also why the next one over does none of it. The label rules. Look for the speed symbol (SS, 10, 20, the Thunderbolt bolt) or the video icon.

Power: USB Power Delivery (PD)

If you take one idea from this piece, make it this one. USB Power Delivery (USB PD) is the specification that lets a charger and a device negotiate how much energy moves between them. Without PD, a standard USB port hands over a modest, fixed amount. With PD, the device asks for what it needs and the charger grants it if it can.

Revision 3.1 of USB PD, announced in 2021, raised the ceiling to 240 W. Before that, the usual limit was 100 W over USB-C at 20 V and 5 A. These are the figures the specification works with:

Voltage	Maximum power	Typical use
5 V – 20 V	Up to 100 W	Charging phones, tablets, light laptops
28 V	140 W	Powerful laptops
36 V	180 W	Demanding gear, monitors
48 V	240 W	High-end laptops, light workstations

Two practical warnings. High power demands a 5 A cable. A random USB-C cable from the drawer will not do. And PD is a separate thing from the proprietary fast-charging systems some manufacturers ship, even though many of them coexist with it. If you are buying a charger for a laptop, read the wattage and look for the words Power Delivery.

Thunderbolt and USB4: cousins with different surnames

Thunderbolt is another specification, created by Intel with Apple, and for years it was the standard for «connect everything with one cable». In its third and fourth versions it uses the same USB-C connector, which is where the confusion starts.

• Thunderbolt 3 and 4 run up to 40 Gbps with video and data at once, and they are the basis of many docks.
• USB4 was born from the Thunderbolt 3 specification Intel handed to the USB standard. They share DNA, which is why they look so much alike. The USB-IF describes USB4 as an architecture that shares bandwidth between data and display dynamically.
• Thunderbolt 5 is the latest generation, up to 80-120 Gbps, aimed at ultra-high-resolution monitors and very heavy workloads.

A practical rule: a Thunderbolt port can always do what a USB4 port does. The reverse does not hold. If you see the lightning bolt symbol, do not hesitate. And when you buy a dock or a monitor, read which version of USB4 or Thunderbolt the maker advertises. That is the difference between driving one 4K display at 60 Hz and fighting with two.

USB, flash drives and other vocabulary traps

«Pass me the USB» usually means «pass me the flash drive», and there the next misunderstanding begins. A flash drive is a storage device that speaks the USB protocol and that the system sees as a removable drive. It is not a port type, and it is not a standard either. The connector on its tip can be USB-A or USB-C, and that changes nothing about what it does.

Keep the layers straight. The port is the socket on the machine. The cable is the medium. The standard fixes speed and power. The device is what you plug in. A USB stick is a device, and calling it a «type of USB» only adds noise.

One footnote from the 2000s deserves a mention. Flash drives were once genuine carriers of malware. Windows autorun launched files the moment you connected the drive, and that turned USB into a well-known infection route. The door is closed by default now. The lesson holds anyway: a storage device is also a messenger, and it can bring more than your files.

How to choose a USB cable without getting it wrong

Run these five checks before you pay for a cable:

1. Check the speed on the label. Forget the «blue is 3.0» rule, because manufacturers break it constantly.
2. Check the power if you plan to charge. A laptop needs a cable and a charger that both support Power Delivery.
3. For video, look for alternate mode. Not every USB-C port outputs to a display.
4. Mind the length. At 40 Gbps, passive cables stop working beyond about a metre. Longer runs need active cables.
5. Distrust the bundled cable. The one that comes in the charger box is usually charge-only and little more.

And if you plan to boot a machine from a USB drive, remember you first have to set the boot order in the BIOS or UEFI.

Frequently asked questions

Are USB-C and USB 3.0 the same thing?

No. USB-C is a connector. USB 3.0 is a speed standard. A USB-C cable can be USB 2.0 only, and USB 3.0 can show up on old type-A connectors. Two independent axes, and mixing them is what gets people into trouble.

Why does my USB-C cable charge but not transfer data?

Because it is a charge-only cable. It does not carry the high-speed data lines. Manufacturers build them that way to cut costs, and they are very common in the box with a phone charger.

What is the difference between Thunderbolt and USB-C?

The connector is the same. The specification is not. Thunderbolt guarantees 40 Gbps and brings extra features, while a plain USB-C port may offer far less. If you see the lightning bolt on the port, it is Thunderbolt.

Is USB4 better than Thunderbolt 4?

They sit at the same speed, 40 Gbps, because they share a base. Thunderbolt 4 adds stricter requirements and Intel certification, and that usually buys you more guarantees at the counter.

Why is USB so confusing?

Because one connector has spanned several generations and speeds, and the naming has been rewritten again and again. USB 3.0 became 3.1 Gen 1, then 3.2 Gen 1, all for the same 5 Gbps. The industry is slowly moving to names built on speed, like USB 5Gbps and 10Gbps, which is the sensible fix.

How much power can a USB-C port deliver?

With USB Power Delivery, up to 240 W in its 3.1 revision, against the earlier 100 W. You still need a compatible charger and a cable rated for 5 A. If either one falls short, the power drops automatically.

The bottom line

USB carries one great virtue, compatibility, and one great defect, terrible naming. The shape of a connector tells you nothing about what it does. What matters is speed, power and video. Before you buy a cable, read those three numbers. Then look at the shape and the colour, if you still care.

And if you enjoy the story of how all this got standardised, take a look at the history of computing. USB was one of the great agreements that stopped every manufacturer from having its own plug.