Simple questions: What is USB (Universal Serial Bus)?

The USB technology has been around for more than 20 years now. We've become so used to it that we take it for granted and we don't consider it special. Although it's almost impossible to have never used a USB device or to have plugged a USB connector into a USB port, it possible that you don't really know what USB means, and what this technology does. You might have heard some acronyms like USB Type C but that's pretty much it. In this article, we will explain what USB is, give you a bit of history about this standard and share the differences between the different types of ports like USB Type C, Micro USB, USB 3.0 and so on. Let's get started:

What does USB stand for?

USB stands for Universal Serial Bus, and it represents an industry standard for cables, connectors and communications protocols, used for the connection, communication, and power supply between various computing devices. It is used by a very large variety of devices, ranging from the common keyboard and mouse to cameras, printers, scanners, flash drives, external hard drives, smartphones, tablets, TVs and so on.


The Universal Serial Bus is a plug-and-play interface, meaning that you can connect a device that has a USB port to your computer, and the computer will be able to automatically detect and install the device, although sometimes you will have to provide the necessary drivers for your operating system. In order to act as a means of communication, USB can transfer data to and from the devices it connects, like from your computer to your keyboard and the other way around.

USB can also supply power to devices. This feature is one of its most useful traits because it allows you not only to make your devices communicate between them, but it also lets you power them or charges the batteries in your devices. For instance, most of the external hard drives we use today, are powered exclusively via their USB ports, without using separate power adapters. Also, smartphones have a USB port that's used both for data transfers and for charging their batteries.

A very brief history of the USB standard

The Universal Serial Bus, or USB in short, was designed in 1996, by several key companies: Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel.


Before USB was invented, computers used to connect to peripherals like keyboards, mice, printers, scanners, cameras and so on, by using various types of ports and connections. For instance, before USB was adopted, keyboards and mice usually connected via PS/2 connectors or by using serial ports. Printers and scanners usually connected via parallel ports. And if you were a gamer back in those days, you also needed a game port if you wanted to play games on your computer using a joystick or a gamepad. Just take a look at the examples from the picture below:


The first USB ports were not capable of high-speed transfers, and hardware manufacturers did not embrace this interface right from the start. But, a few years after it was first developed, the USB interface was revised by the companies that created it, and they made USB version 2.0, which was a lot faster. Because of that, after the year 2000, the USB port saw a massive expansion and it is now found on all kinds of devices. Since then, USB has become the main way of connecting devices and transferring data between them.

USB versions and data transfer speeds

Since it was first developed, the USB interface kept on getting faster with each revision. Here are the main revisions or versions of USB:

  1. USB 1.0 and USB 1.1- were the first iterations of the USB interface, released in 1996 and 1998 respectively, and they were capable of data transfers of up to 1.5 Mbps, respectively 12 Mbps. At the time when they were developed, USB 1.0 was also known as Low Speed USB, while the USB 1.1 was known as Fast Speed USB.

  2. USB 2.0 - also known as Hi-Speed USB, was released in April 2000 and it supports maximum theoretical data transfer speeds of up to 480 Mbps. In reality, the maximum effective throughput is limited to 280 Mbps or 35 MB/s. USB 2.0 is backward compatible with USB 1.0 and USB 1.1, meaning that you can use old devices with USB 1.x ports to connect to newer devices that have USB 2.0 ports.

  3. USB 3.0 - came to life in November 2008 and it is also known as SuperSpeed USB. It can support theoretical data transfer speeds of up to 5 Gbps, but the real-life speeds you can get on it are around 3.2 Gbps or 400 MB/s.

  4. USB 3.1 - was released in July 2013 and is also known as SuperSpeed+ USB. It is capable of theoretical data transfers of 10 Gbps, double that of USB 3.0. In reality, the maximum achievable transfer speed is of 7.2 Gbps or 900 MB/s.


How do I differentiate between USB 3.x ports and USB 2.0 ports?

To differentiate USB 3.x ports from USB 2.0or USB 1.x ports, the USB 3.x ports are usually colored blue. The previous versions of USB - USB 2.0and USB 1.x - were usually painted black.



Types of USB connectors and ports

There are many types of USB ports and connectors, and before we show you the most common, let's see first what's the difference between a USB port and a USB connector:

  • A USB connector is the end of a USB cable that connects to a USB port.
  • A USB port is a location on your computer or device into which you plug a USB connector.

Here are the most common USB connectors:

  • USB Type A - is the most common type of USB connector and port. This type of port is probably found on the majority of computers and laptops. The connector is large and bulky, found at the end of the USB cable that you will plug into your computer. This USB Type A appeared together with USB Type B, when the first USB specification was released, in 1996.

  • USB Type B - probably the largest USB connector out there, the USB Type B is square shaped, with two small bevels on two of its corners. The USB Type B connector is generally used at the end of the USB cable that plugs into your printer, scanner, and other large devices.

  • Mini USB - are smaller versions of the USB Type Aand USB Type B connectors. They were introduced in 2000. However, Mini USB connectors are very rare these days, as they became outdated by the newer Micro USB connectors.

  • Micro USB - are even smaller than Mini USB connectors and are the most widely used USB connectors today, especially on smartphones and cameras. They were introduced in 2007.

  • USB Type C - is the newest version of a USB connector, released in 2014, and it's characterized by three things: it's small, it's reversible, and it's generally used for USB 3.1 ports. The USB Type C connector was created roughly at the same time when the USB 3.1 was released, hence the common mistake people make to assume that USB 3.1 and USB Type C are one and the same. In reality, they're not, as USB 3.1 is a USB protocol, while the USB Type C is a connector specification. Although it's not very common, some devices can use USB Type C connectors but only support USB 2.0. All things considered, the future is all about USB 3.1 and USB Type C, so you should expect more compatible devices being launched on the market.




Now you have a clearer idea of what USB stands for and why it's useful. Also, you know how this standard has evolved over time and the differences between the many types of USB connectors. If you have any questions about this subject, don't hesitate to ask using the comments form below.

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