compatibility - Does the device that supports USB 3.0 work via computer that supports USB 2.0

I am planning to buy external hard drive that supports USB 3.0. Will it work with my old notebook that has USB 2.0?

Answer

Yes, USB 3.0 is backwards compatible. However, some new instructions are added to the new 3.0 standard so some functionality might not work. However, most hardware will support USB 2.0 and I won't expect too much problems with an external hard drive.

Reference from PCWorld:

The beauty of USB 3.0 is its backward compatibility with USB 2.0; you need a new cable and new host adapter (or, one of the Asus or Gigabyte motherboards that supports USB 3.0) to achieve USB 3.0, but you can still use the device on a USB 2.0 port and achieve typical USB 2.0 performance.