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The Complete Guide to USB Types

Almost every computer or laptop you use will come with a USB port. Also known as the USB connector, this hardware interface is designed to support a range of devices, providing a link between the computer and peripherals such as keyboards, mice, external storage devices and printers.

Different USB cables fit into the different ports. This is because there are multiple types of USB ports that are built into computers and laptops.

If you're looking for information about the different types of USBs, this guide will take you through everything from what USBs are to connector types that you might come across. Once you know the various types, you can use our guide to different protocols to determine the USB ports you're working with.

What does USB stand for?

USB stands for Universal Serial Bus. The acronym refers to both the port and the plug end of a USB cable. USBs have become everyday essentials for those using computers across a range of industries and in a variety of settings.

Although its name indicates that it's a 'universal' solution, there are different types of USB ports.

What was a USB used for originally?

While it might appear that they've only become popular in the last decade, USB ports and devices were first launched in 1996. The aim of the first incarnation – USB 1.0 – was to create a standardised means of connecting peripherals to computers. They were originally designed for personal computers, linking low-power hardware like keyboards and mice.

But over time, USBs went from transferring 1.56Mbps at a power transfer rate of 100mA to data transfer of up to 40Gbps and a power transfer rate of up to 5A for the latest USB version, 4.0, which was launched in 2019.

Why did USBs become popular?

As they increased in capacity and power, USBs became a common means of connecting other devices that needed more electrical current, like mobile phones and tablets. Soon, some of the original ways of connecting devices to computers, such as parallel ports and serial ports, were replaced by USB connectors. This occurred on desktop computers used in offices as well as on personal computers.

Several advantages come with using USBs:

  • USBs automatically configure to the computer or device they're plugged into, so there's no need to update any settings or change the format to make everything work properly. To do this, the USB accesses existing drivers or the system will indicate to the user that they need to locate a relevant driver.
  • Most USB devices can be easily inserted and removed. Flash drives are the main exception to this rule. Here, users must safely eject the device to avoid potentially losing data that's been saved to the memory stick.
  • Most devices are set up to slot into USB ports. This makes transferring data or operating external hardware easier.

Ultimately, USBs took over from the earlier connectivity ports because they deliver more power and they're easier to use. Their design is simple, and connectivity is typically faster.

What is a USB used for today?

Today, USBs have several functions. Some are designed to transfer data quickly, others can charge devices. USB ports also continue to do their original job, which is to connect hardware including printers, scanners, keyboards and mice, along with joysticks and monitors, to a range of devices.

Thanks to the advanced connection speeds, faster data transfer times, and increased power that they offer, USB ports can also connect mobile devices to computers and laptops. Here, data is transferred between the two computers via the USB link.

The advent of the flash drive four years after USB version 1.0 was launched also meant that floppy discs became obsolete. Flash drives were easier to transport and advances in technology meant that they could store not only megabytes but – eventually – terabytes.

As well as computers and tablets, USB ports can be found on a range of technical equipment used around the home as well as in professional settings. Cars, modern games consoles, and audio-visual equipment such as TVs all have USB connector types built in.

What are the USB connector types?

There have been several major updates to the original USB over the decades. To understand which USB port you're working with, it's worth having an idea of the major differences between these different USB connector types.

One indicator of the USB type that you need is the shape of the plug. This will show you what type of USB port it fits into. Both the port and the plugs that fit in them come in different shapes and sizes. To help, here's a look at the key versions to be aware of and how to spot the type by looking at the shape of the plug.

What is USB-A?

USB type A is the flat, rectangular USB port and plug that's the most common connector type. It's used to connect most peripherals and the connection is held in place by friction. This makes it easy to connect the USB cable to the port.

Round pins were the main connection contacts for predecessors to USBs, such as parallel ports. With USB-A, flat contacts at the terminals slide together when the male plug is inserted into the female port. The USB-A terminal block is positioned in a way that means there is only one way the plug can be inserted.

They can easily be repeatedly attached and removed while maintaining functionality. Most computers have at least one USB-A port, although it's typical for there to be several so that users can plug in various peripherals at once.

As this is the classic USB design, type A is compatible with all versions from 1.0 to 3.2. It was only in 2019 that this changed, and the USB 4.0 standard required a different USB connector – type C.

What is USB-B?

USB type B ports are almost square, rather than rectangular like type A. The corners of a USB-B connector and its plug are angled, and this makes it easy to see the correct way to insert the plug into the socket.

Where type A USBs are found on computers, type B is located on peripheral devices that are designed to connect directly to the host device, such as scanners and printers. Most USB type B plugs are at one end of a cable, which is inserted into the peripheral. At the other end is a USB type A, which can then be inserted into the computer.

What is USB 3.0?

USB 3.0 has been around since 2008. It offered faster speeds of up to 5Gbps, known as SuperSpeed.

Most USB types, apart from version 4.0, are compatible with all generations, however, newer ports are faster.

Since its launch, version 3.0 has undergone two updates. In 2013, version 3.1 offered transfer rates at double the speed, coming in at 10Gbps. This was followed by version 3.2 in 2017, doubling up again to 20Gbps. Both of these updated versions refer to the faster transfer times as SuperSpeed+.

To use USB version 3.0, look out for the blue USB type A port. However, version 4.0 of the USB standard was launched in 2019. Products supporting USB 4.0 were rolled out in mid-2020.

Many laptops and computers have ports for 2.0 and 3.0-compatible devices. Plug slower peripherals such as your keyboard and mouse into the 2.0 slot and choose the 3.0 slot for faster devices like hard drives.

What is USB-C?

USB type C shares similarities with type A in how it functions and its purpose. However, this is much smaller than its predecessor, with curved edges and a less clunky design. USB-C is one of the newest and fastest USB connector types available.

As well as being faster, female USB-C ports can accept a male USB-C plug either way round. This is because the terminals on both the port and plug are symmetrical.

Unlike the other types, USB-C is compatible with USB 4.0. USB-C cables have been introduced to connect with newer smartphones, tablets, PCs and other hardware devices that have the USB-C port already built in. Type C is gradually replacing type A, as well as USB-B.

This replacement is largely down to this USB type delivering more power and speed. USB-C has an upper limit of up to 40Gbps, and type C ports also support power delivery of up to 20V and 100W. This makes them ideal for fast data offloading and rapid charging of modern peripherals, such as the latest smartphones.

While USB-C appears to be replacing other types of USB connectors, it can be used with adapters and cables that connect with other versions. They can also transfer power and data between all previous generations of USB devices. This makes USB-C the closest to being a truly universal point of connection between devices and computers.

Other connectors

You may come across other USB types. These aren't as common, but they could feature as part of your device. Some to look out for include:

  • A Micro USB or Micro-B connector: This is commonly found on rechargeable technologies and smaller hardware peripherals
  • Micro USB-A: These are mostly found on newer devices that don't have a faster type C port
  • Mini A/B: This is a connector that can accept either mini A or mini B plugs and cables
  • USB converters and adapters: Such as A to A, B to B, A to B and B to A

Know the difference

By understanding the difference between the different USB types, it's possible to narrow your search. To further determine which port you need for your device, take a look at our guide to the protocols.

Knowing the type of USB you need can make it easier and faster to complete the task you're working on. Generally, the newer the model, the faster the USB port is likely to be.

I'm a Mechanical Engineer by qualification though I worked for a long time specialising in Motion Control systems and integration with various PLC systems. I've wide experience of many types of applications from packaging machines to military and some applications that I can't mention. At home, I like to tinker and make things with wood, metal, plastics, electronics and mechanical system. I'm never happier than with a hammer and a screwdriver in my hands....
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