The initial versions of the USB standard specified connectors that were easy to use and that would have high life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of the USB standard gave rise to another family of connectors to permit additional data links. All versions of USB specify cable properties. Version 3.x cables, marketed as SuperSpeed, added a data link; namely, in 2008, USB 3.0 added a full-duplex lane (two twisted pairs of wires for one differential signal of serial data per direction), and in 2014, the USB-C specification added a second full-duplex lane.
USB has always included some capability of providing power to peripheral devices, but the amount of power that can be provided has increased over time. The modern specifications are called USB Power Delivery (USB-PD) and allow up to 240 watts. Initially USB 1.0/2.0 provided up to 2.5 W, USB 3.0 provided up to 4.5 W, and subsequent Battery Charging (BC) specifications provided power up to 7.5 W. The modern Power Delivery specifications began with USB PD 1.0 in 2012, providing for power delivery up to 60 watts; PD 2.0 version 1.2 in 2013, along with USB 3.1, up to 100 W; and USB PD 3.1 in 2021 raised the maximum to 240 W. USB has been selected as the charging format for many mobile phones and other peripheral devices and hubs, reducing the proliferation of proprietary chargers. Since USB 3.1 USB-PD is part of the USB standard. The latest PD versions can also provide power to lower power laptops.
