Also known as: Universal Serial Bus, USB-C
USB (Universal Serial Bus) is the most common standard for connecting peripherals to a computer and for delivering power, using a hot-pluggable, host-controlled serial bus.1
Overview
A USB system has one host (the computer) that controls a tree of devices through hubs — keyboards, mice, drives, cameras, dongles. Ports are hot-pluggable, so devices can be attached and removed while running. Successive versions (USB 2.0, 3.x, 4) raised speeds by orders of magnitude, and the reversible USB-C connector added high power delivery (USB-PD), letting one cable both run and charge a device. It is part of a machine’s I/O, distinct from internal expansion buses like PCIe.
What it’s for
USB is how most external hardware reaches the CPU: a single cable carries data and often power to a peripheral. It is central to SDR — an RTL-SDR dongle plugs into a USB port and streams IQ samples to the host, and many capture nodes are powered over the same USB connection. The trade-off versus internal buses is bandwidth and latency: convenient and universal, but a USB link will not match a dedicated PCIe slot for raw throughput.