USB Version Numbers
There are a number of different USB version numbers (1.0, 1.1, 2.0, and 3.0). This indicates their transfer speed. The higher the version number, the faster they can work. However, to get the full power, the "host", the device and the cable must have the same version. If not, the lowest USB version in the chain will control the speed.
For example,if your computer has a 2.0 USB port, your cable is 3.0, and your phone is 3.0, you will achieve 2.0 speed. If all three (computer, cable and phone) have 3.0 then you will achieve 3.0 speed.