Whenever you plug-in a new hardware via the USB to your PC, the windows based operating system detects it and asks you for either searching for its drivers or else asks you to add the drivers manually, out of which the automatically install drivers is more preferable because in this way the drivers of the latest version would be downloaded and installed for the added device.

If the system cannot find any drivers for the added device, which generally happens when you are trying to install drivers for a device which is not branded and has to be installed with the CD which is offered by the manufacturers.

Following this you will be asked to locate and install drivers manually from your local computer or else to check for a solution online, which is again a windows feature to make sure that the minimum drivers are installed to make the device working.

If the drivers are still not found then windows starts searching for the drivers online and also offers you with a option to install the drivers later whenever you have the drivers CD available.