Somehow I feel compelled to comment here...

USB has been a near train wreck of design by committee mis-steps all along the way. While some may be impressed by how much better USB is than what came before, the innumerable connectors, versions, speeds and configurations make your head spin.

Maximum 500mA USB original current draw spec when external portable hard drives of the era needed at least twice that? Sure, just create a non-standard three headed USB cable!

USB B connector too large to fit into a peripheral? OK, we will make a whole series of non-interchangeable derivatives. Mini USB B, Micro USB B, 5-pin Mini, MHL video USB, and so on.

Then there is A, Mini-A, Micro-A, etc, not to mention USB On-The-Go

USB 3.0 grafts a whole other connector alongside the existing peripheral connector, for better backasswards compatibility. Again, in multiple connector sizes.

How shall we name the cable speeds?
Low-Bandwidth
Full-Bandwidth
Hi-Speed
Super-Speed
SuperSpeed+

How to tell which existing USB cable will work with which new-to-you device? Not so easy...

USB chargers? Multiple 'standards' to indicate charger current capacity, plus Apple's method. Charge a Motorola phone using that Nokia USB car charger? Maybe not...

So now we shall have;
Quote:
... In July 2012 the USB Promoters Group announced the finalization of the USB Power Delivery ("PD") specification, an extension that specifies using certified "PD aware" USB cables with standard USB type A/B connectors to deliver up to 100 W of power at 20 V. For PD-aware cables with USB-micro B/AB connectors the maximum power supported is up to 60 W at 20 V, 36 W at 12 V and 10 W at 5 V. In all cases, either host-to-device or device-to-host configurations are supported.
I am sure users will have no trouble sorting out what cables go with what devices for what purposes... /s