You are sometimes given a disk image that needs to be written to a USB thumbdrive or a SD card. This is typically used to create something that you can use to boot a device. The image file typically has the .img file extension, though its not necessary and does not matter.
- One way to write a disk image on Windows is using Win32 Disk Imager. Download it and unzip the contents.
- Plug in the USB thumbdrive or SD or microSD card to your computer. It should be detected and appear as a drive in Windows.
- Open Win32 Disk Imager, choose the .img or image file you want to write as Image File and choose the USB or SD drive as Device and press Write.
- The write may take a while. Once it is done, remove the USB thumbdrive or SD card and insert it into the device you want to use with.
Also see: How to write a disk image on Linux
Tried with: Win32 Disk Imager 0.8 and Windows 8 x64