usb

USB, short for Universal Serial Bus, is a standard for connecting computers and peripheral devices. Introduced in the mid-1990s, USB streamlined connections by providing hot-swappable peripherals, simplified cabling, and scalable data transfer and power delivery through a single interface.

Core generations began with USB 1.0/1.1 (1996–1998), offering up to 12 Mbps. USB 2.0 (2000) introduced 480 Mbps, while USB 3.0 (2008) added 5 Gbps. Subsequent revisions raised speeds toward 10–20 Gbps with USB 3.1/3.2, and USB4 (finalized in 2019) reaches up to 40 Gbps and supports PCIe and DisplayPort tunneling. USB-C, a reversible connector, has become the common physical interface.

Connectors and power: The familiar USB-A is common on hosts, while devices use USB-B, micro-USB, or USB-C. USB-C supports higher power delivery, up to 100 watts via USB Power Delivery, enabling charging notebooks and other devices. USB devices may be bus-powered or require an external supply and may be connected through hubs.

Architecture and operation: USB is host-centric, organized in a hub-and-tree topology with a host controller at the root. It supports multiple transfer types—control, bulk, interrupt, and isochronous—and emphasizes plug-and-play and hot swapping. Power management, data negotiation, and device classes enable broad interoperability across peripherals.

Impact and outlook: USB has become a ubiquitous standard across computing and consumer electronics, enabling keyboards, mice, storage, cameras, and docking stations to interoperate widely. Ongoing development focuses on higher speeds, greater power delivery, compact connectors, and stronger security guarantees, with the USB Implementers Forum maintaining specifications.