USBliittymien

USBliittymät, or USB interfaces, are standardized connectors that enable communication and power delivery between electronic devices. The Universal Serial Bus (USB) specification was first introduced in 1996 to provide a simple, universal method for connecting peripherals to computers, reducing cable clutter and simplifying device setup. Over time, the protocol evolved through several versions: USB 1.0 (low‑speed 1.5 Mbps and full‑speed 12 Mbps), USB 2.0 (high‑speed 480 Mbps), USB 3.0 and 3.1 (super‑speed 5 Gbps and 10 Gbps), USB 3.2 (multi‑lane operation up to 20 Gbps), and USB 4, which builds on Thunderbolt 3 technology to support speeds up to 40 Gbps. Each newer version maintains backward compatibility with earlier ones while adding improved data transfer rates, power delivery, and support for alternate modes such as DisplayPort and HDMI.

USB connectors are classified by shape and interface rating. Common types include the larger Type‑A and Type‑B connectors used on desktop PCs and printers, the smaller micro‑USB and mini‑USB connectors found on older mobile devices, and the versatile USB‑C connector introduced in 2014, which supports reversible insertion, higher power delivery (up to 100 W), and multi‑protocol functionality. The USB protocol defines host and device roles; a computer or hub acts as a host supplying power, while peripherals such as keyboards, mice, and storage devices act as devices receiving power. USB also supports On‑The‑Go (OTG) mode, allowing devices to switch roles to connect directly to one another without a host. Power delivery specifications now enable fast charging for smartphones, tablets, and even laptops, with negotiated voltage and current levels ranging from 5 V/0.5 A up to 20 V/5 A or more.