Ah, junk drawers. An invention or discovery? A philosophical question that perhaps only I have ever wondered about. Regardless, I’m willing to bet that besides dozens of takeout menus, a flashlight that doesn’t work and an inordinate number of rubber bands, this space that is never not full, holds more cables than you have devices. How did this happen? Why are there so many different sizes, colors, and connections? It’s a good bet that they all have at least one thing in common. No, not that they’ll stay in that drawer forever. Of course they will. It’s that they’re all USB cables.
That little cable has become so ordinary that we barely think about it anymore. But behind that rectangle is one of the most successful tech standards in history—one that helped drag the world’s devices out of the cable chaos of the ’90s and into something resembling order. Today we’re talking about USB: how it was born, how it works, and how it ended up powering just about everything you own.
I’m Chris Rouman, and I’m Nerd Adjacent.
What is it?
USB stands for Universal Serial Bus. It’s “Universal” because it was meant to work for everything. It’s “Serial” because it sends data one bit at a time. And finally, it’s a “bus” because in computing, that’s the shared pathway that carries data between devices. If we translate this nerd-speak into normal-people-speak, it means having one standardized way to connect all kinds of devices to your computer.
In the early days of personal computers, every peripheral had its own specific connector. Printers used big, clunky parallel ports. Keyboards and mice used PS/2 ports. External drives used yet another connector. If you were lucky, setting up new hardware only took a couple of hours and a reboot or two…or ten.
In 1994, seven companies–Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel–formed a working group to propose a single, simple port that could handle everything: power, data, and communication. After forming the USB Implementers Forum, USB 1.0 launched in 1996. At first, it didn’t exactly take the world by storm. Most PCs didn’t ship with USB ports, and few accessories supported it.
Then, in 1998, Apple released the original iMac. And in typical Apple fashion, they made the bold decision to ditch all the old ports. It came with only USB. If you wanted to make a keyboard, mouse, or printer that worked with the new iMac, it had to use USB. That gamble forced the entire industry to adapt. And once it did, there was no going back.
Within a few years, USB had replaced almost every legacy port on the back of a PC. And it earned its reputation as something truly radical: you could just plug something in and it worked.
How does it work?
At its core, USB is designed around simplicity and standardization. The connector has a few key wires that handle data and a couple that handle power.
When you plug in a USB device, the host computer first provides power and then initiates enumeration, which is a structured conversation to identify what the device is.
The host asks:
- Who are you? (Vendor and product ID)
- What kind of device are you? (Keyboard, storage, camera, etc.)
- How fast can you talk? (Low, full, high, or super speed)
- How much power do you need?
- And crucially: What kind of data transfers do you require?
A PC, keyboard, and USB cable walk into a bar. The USB plugs itself into the PC. And the PCs like, ‘what, no dinner first?” And then the USB cable asks the keyboard, get this, ‘how much power do you need?’ And the keyboard says, with a totally straight face, ‘oh, about 100 milliamps.’ Then Mr. USB asks, ‘ok, well what kinda data are you sending?’ And the keyboard says, ‘scan codes of course!’
That last part––communicating data transfers––determines how the host will handle the data stream. This is important because not all data is created equal. A USB keyboard and a USB webcam both send data, but their needs couldn’t be more different.
USB defines four transfer types, each optimized for a particular use case:
- Control transfers are used for device setup and configuration. An example of this is when the computer asks, “What kind of device are you?”
- Bulk transfers are for large amounts of data that can tolerate delays and are used by things like flash drives and printers.
- Interrupt transfers are used by keyboards, mice, and game controllers that require small, time-sensitive bursts where each keypress needs to register immediately, even if it’s just a few bytes.
- Isochronous transfers are for things that need continuous, time-critical streams like microphones, webcams, and speakers. These things need consistent timing, even if a few bytes get lost.
By handling data based on its purpose, USB replaced dozens of legacy ports with a single, flexible system that adjusts on the fly.
That’s what made USB such a breakthrough: your computer didn’t need separate hardware for sound, storage, or input anymore. One port could do it all because it understood what kind of data it was dealing with.
So the introduction is how the device says, “Hey, I’m a microphone. I care more about steady timing than perfect accuracy,” or “I’m a flash drive. Take your time, but don’t lose a single bit.”
This conversation happens in milliseconds, and then—tada—it’s connected.
The “plug and play” experience we take for granted today really started with USB. But that simplicity came with quirks—starting with the shape of the plug.
The original USB connector, the rectangular Type-A, only fit in one direction. That wasn’t meant to torment us; it was just cheaper and easier to manufacture. A small price to pay for the ease of plug and play.
As the standard evolved, new versions appeared: USB 2.0, then 3.0, then 3.1, and 3.2. Each one was faster and more capable, but also more confusing. Color-coding the ports for different versions was intended to ease the confusion, but most people had no idea what they meant.
In a world of chaos and oddly shaped connectors comes the savior humanity has been looking for. This weekend, see the movie that will reshape how you think about connecting stuff to your computer. Connector Mayhem! Your workday will forever be changed. Rated N for super nerdy language and dad jokes.
As it turns out, the “universal” part of USB only applied to the end you plug into your computer: the rectangular Type-A connector. This was to guarantee a consistent power and data interface across all hosts regardless of the device end. In this way, the USB standard actually allowed device makers to define their own connectors within certain electrical constraints. The rationale was that different devices had different physical and mechanical needs. A tiny MP3 player couldn’t fit a full-size USB-A port, while a printer needed something sturdier.
So companies came up with all sorts of connectors:
• Type-B (the squarish printer one)
• Mini-B (for early digital cameras and phones)
• Micro-B (for slimmer smartphones and external drives)
Every time devices got smaller or thinner, a new “B-side” plug emerged, often with proprietary tweaks to lock you into a brand’s accessories. The USB working group didn’t want to push too hard. Adoption mattered more than purity.
It took nearly twenty years and several frustrated consumers before the industry finally agreed on one port to rule them all: USB-C. Reversible, powerful, and compact, it could handle data, video, and power—and finally delivered on the “universal” promise.
Why it matters
For those that remember a time before USB, connecting stuff to your computer could be frustrating and time consuming. Not only that, it was also entirely possible that your PC didn’t even have the correct port for you to plug into! That was fun. USB helped to usher in the adoption of new gadgets: digital cameras, external drives, MP3 players, and flash drives. It made “plug and play” not just a slogan, but an expectation.
But that’s not all! Enabling gadgets to communicate with your computer was one thing. But once manufacturers realized those same cables could deliver electricity, USB became the world’s charging standard.
Phones, speakers, keyboards, cameras—all of them could draw power through that same five-volt line. It even reached beyond computers: cars, airplanes, hotel lamps, airport seats were all built with USB ports to keep our devices alive. USB unified how our tech connects, communicates, and charges. It became invisible infrastructure; the plumbing of the digital world.
And as it evolved, it became a quiet symbol of cooperation in tech. Competing companies actually agreed on something. Intel, Microsoft, Apple, HP—they all adopted and improved the same standard rather than inventing their own. That collaboration made the modern ecosystem possible.
And now, thanks to the European Union’s 2024 regulation requiring USB-C on all phones, we’ve reached a new level of universality.
Even Apple—famous for doing things its own way—finally gave in and put USB-C on the iPhone 15 in 2023.
It took thirty years, but the dream of one connector for everything actually came true. Of course, nothing lasts forever. Wireless charging and data transfer are becoming more common. Apple’s already experimenting with completely portless designs.
But USB has already done its job. It bridged the gap between the messy, incompatible computers of the past and the seamless, wireless future we’re heading toward.
Conclusion
So the next time you reach for a cable, whether it’s to charge your earbuds, your laptop, or your toothbrush, remember that you’re using a technology that quietly changed how the world connects.
USB outlived FireWire, serial ports, parallel ports, and dozens of other standards. It made the phrase “just plug it in” possible. And it became one of the rare examples of tech that truly lives up to its name: universal. It’s also a reminder that progress isn’t always elegant. Sometimes it’s a long series of awkward prototypes, confusing names, and upside-down plugs before getting it right.