USB Standards
USB standards separate data transfer and power delivery into two independent systems. The physical connector determines what is possible in hardware, but the actual capabilities depend on which protocols both connected devices mutually support — negotiated automatically at connection time.
Connectors The physical plug and socket (Type-A, Type-C, Micro-B, etc.). A connector type sets the maximum possible speed and power, but does not guarantee any particular protocol support.
Data protocols USB 1.0 through USB4 Gen 4 define transfer speed in Gbps. Speed depends on the cable, the host, and the device all supporting the same generation. A USB4 port with a USB 2.0 cable runs at USB 2.0 speed.
Power protocols Charging speed is negotiated separately from data. USB PD (Power Delivery) is the open standard; Quick Charge, Apple Fast Charge, and others are proprietary alternatives. A charger and device must share a protocol to charge faster than the 5 W USB default.
Alternative modes USB-C can carry non-USB signals over the same cable — DisplayPort, HDMI, Thunderbolt, and more. These are negotiated at connection time and require support from both the cable and the connected devices.
The charts below show each category sorted chronologically so you can follow how capabilities evolved over time.