an off-topic here:
what is the difference between an OTG cable and a normal microUSB-to-USB adaptor cable?
I have the normal one, will it work?
OTG stands for on-the-go. New feature of the USB protocol that allows your phone to be a host. A phone typically is a slave device in the host-slave relationship. Host being a PC, and slave being devices like flashdrives, mouse, keyboard, etc.
For the phone to function as a host, you need a female USB Type-A connector, which this adaptor provides. The microUSB to USB cable works with your phone as a slave, ie connecting it to a computer for charging, data syncing, etc.