Unable to understand USB 2.0

Hello,
I have desktop computer. I am using USB devices to transfer data. It takes too much time to transfer any data to the USB device. One of my friends asked me whether my USB is USB2.0 or not. I can not understand what is this?
How can I find out that whether it is USB2.0 or not?
I need some help to do this thing.
Please help me by telling how I find out the USB criteria.
