USB Standards

USB 1.0, USB 2.0, USB 3.0. What does it all mean?

USB 1.0 – Where it all started

USB standards (starting with USB 1.0) were first released in 1996 but not much was done using USB until USB 1.1 came along a couple of years later. Maximum data transfer speed of these standards was 1.5Mbps (Megabits per second). Keep that number in mind as you work your way down the page. USB offers outstanding capability, allowing multiple peripheral devices to be connected at once. As the standards improved over time, backward compatibility was built in so you could always use older cables and devices with newer cables and devices, but they would be limited by the maximum data transfer speed of the oldest standard device/cable in the chain.

USB 2.0

USB 2.0 came along in 2000 and took the maximum data transfer rate up to 480MBps. This is when the use of USB really started to take off with a quantum leap in speed. Type A USB connectors that are black are USB 2.0.

USB 3.0

in 2008 another huge leap came along, with maximum data transfer speeds of 5.0Gbps – or ten times faster than the USB 2.0 standard. Again, backward compatibility meant that all of your existing cables and devices could still be used and then upgraded as needed. For reference, a standard definition movie would take over 2 hours to download using USB 1.0, or about as much time as it would take to watch it. Ahhh… the good old days. USB 2.0 cut that down to a few minutes. But USB 3.0 reduced your wait time to under 30 seconds! That’s not even enough time to make the popcorn. USB Type A connectors that are blue are USB 3.0 or later. This was the first standard that was labeled SuperSpeed, and sometimes has the SS logo on the connector.

USB 3.1 and USB 3.2

When USB 3.1 came along the transfer rate was increased to 10Gbps. USB 3.2 took that up to 20Gbps. Some, but not all, connectors will have SS10 or SS20 printed on the connector.


You likely didn’t notice, but there is no space between USB and the number 4. This re-branding is intentional. USB4 is currently undergoing review (early 2020) and will offer data transfer speeds of up to 40Gbps. USB4 uses the USB C connector exclusively as the electronics world transitions to USB C. Perhaps the single biggest advantage of USB4 is the ability to have a USB C connector at each end of the cable. One cable to rule them all! Another standard that uses the USB C connector is Thunderbolt 3, which was developed by Intel. I’ll talk about Thunderbolt 3 in a moment. USB4 will offer much of the capability of Thunberbolt 3 and should be compatible with almost all Thunderbolt 3 use cases.

Thunderbolt 3

Intel developed the Thunderbolt 3 standard independently of the USB Implementer’s Forum (USB-IF). The great strength of Thunderbolt 3 (and ultimately USB4) is the ability to transfer data, and power through one cable. Plug your Thunderbolt 3 laptop into a dock with your USB C cable and you’re good to go. Remember, it can handle up to 100 watts of power, so you can charge your laptop quickly and easily while getting work (or play) done. Look for the Thunderbolt logo on the connector, typically with the number 3.

USB connectors

This is the stuff that most people don’t care about, but it’s also the reason that you may own a USB cable that doesn’t do what you thought it should.

USB connectors

First USB stands for Universal Serial Bus. Now you can see why it’s abbreviated. Very simply, a technology bus works kind of like a bus in the real world: it transports stuff between two places, in this case two devices. A USB cable can carry data and power between your charger, your computer, or your car, and your phone.

USB Type-A

USB Type-A (or USB A) was originally designed to be plugged into the computer, with USB Type-B (or USB B) to be plugged into the connected device. They were designed this way so that there would be no confusion as to which plug went where.

USB Type-B

As USB standards developed, capabilities improved and smaller connectors became needed, especially with the advent of mobile phones. I’ll skip through some of the variations, but the initial standardized connector used on mobile phones (other than the iPhone, which I’ll talk about shortly) was the USB Micro B. Prior to 2007 most early mobile phone makers used proprietary connectors.

USB Micro B

As technology progressed, the mobile phone world (along with tablets and laptops) moved on to USB Type C.

USB Type-C

One advantage of USB C is that there is no right side up. Also, newer devices (and vehicles) can support USB C at both ends of the USB cable which provides better performance and power. Apple has already moved to USB C for iPad Pro. And Thunderbolt 3 (which uses a USB C connector, but I’m getting ahead of myself) for MacBooks. (More about Thunderbolt in a future post.)

So that’s a quick review of the available USB connectors.

“Wait… what about Lightning?!” I hear many of you saying. Apple’s Lightning connector is not technically a USB connector, although it does have pins that pass USB data and power. This is why you can find Lightning to USB adapters. In fact, Apple has gone it’s own way with connector types since they first developed computers. Just as a recap, the first iPhone used a 30-pin proprietary connector designed by Apple.

Apple 30-pin Dock Connector

The Apple 30-pin Dock Connector was used on the original iPhone through the iPhone 4, along with iPods and iPads. The iPhone 5 saw the introduction of Apple’s Lightning connector.

Apple Lightning connector

One of the reasons that genuine Apple Lightning cables and adapters are so expensive, is that there’s actually a processor built in. This is why you can plug it in either way and it just works. Also, this is why some inexpensive cables that are not MFi certified don’t work properly. They don’t have the processor. It can be confusing because it seems that your cable works intermittently. What’s happening is that sometimes you plug it in one way and it works, and sometimes you plug it in the other way and it doesn’t work. That’s because they left out the processor, so it only works properly half the time but allowed them to sell it for less. (Here’s a little secret if you have one of these Lightning cables already: mark the connector on one side so you always plug it in the same way.) I’ll talk about why some of your other USB cables don’t work in my next post about USB standards.

The USB Implementers Forum (USB-IF) currently has representatives from seven technology companies, including Apple and Intel. This non-profit organization ensures that everyone is on the same page regarding USB compliance. At least everyone that chooses to comply with USB standards, which I’ll talk about in my next post.