USBrajapinnat

USBrajapinnat (Finnish for "USB interfaces") refers to the family of Universal Serial Bus physical connectors, signalling standards and protocol layers used for communication and power delivery between computers, peripherals and consumer electronics. Introduced in the mid-1990s to replace a variety of legacy ports, USB standardized connector types and bus protocols to simplify device interconnection and hot-swapping.

USB interfaces are defined by connector form factors (such as Type-A, Type-B, Mini and Micro variants, and the reversible Type-C), protocol versions (USB 1.x, 2.0, 3.x, and USB4) and power-delivery specifications. Data transfer rates have evolved from 1.5/12 Mbit/s (Low/Full Speed) through 480 Mbit/s (High Speed), multi-gigabit speeds in USB 3.x (up to 20 Gbit/s depending on the revision), and up to 40 Gbit/s in USB4 entries that integrate Thunderbolt 3 compatibility. USB Power Delivery (PD) allows dynamic negotiation of voltage and current over compatible connectors, enabling device charging at higher wattages.

USBrajapinnat support multiple device classes (storage, input, audio, network, video) and features such as isochronous transfers for real-time streams and alternate modes that permit non-USB protocols (e.g., DisplayPort) over the same physical link. Backward compatibility is a core design goal, though adapter and cable wiring may affect supported speeds and power. The USB Implementers Forum (USB-IF) maintains specifications, compliance testing and branding to ensure interoperability across manufacturers.