Right now there are three generations of USB out in the wild, with a fourth as yet unreleased, but in the works. That means the computer, the cable and the device must all comply with that particular USB standard for it to run as well as possible.

When you buy a USB peripheral, it will specify which the highest standard is that it supports and – sometimes – requires. Which means that some devices simply won’t work properly because they can’t push data through the cable quickly enough. The worst that can happen is that it defaults to the oldest, slowest standard that both devices can understand. In practice this means that if a USB cable fits into a port, it will work. Yet, a key part of USB is the “universal” bit. The hardware that sends and receives information is faster and the internal wiring differs significantly. That’s because USB standards have improved over the years. It’s important to understand that although two USB ports and cables might look identical, it doesn’t mean they have the same capabilities.

Usb 2 vs usb 3 wiring