The root of an SD card is the highest level of storage, which is the base folder of the card. It is also referred to as the "main," "parent," or "top" folder of the SD card. When you access an SD card with your devices file explorer, the root folder is the first folder that shows up, and it contains general folders such as DCIM. If you move files to an SD card without putting them into a specific subfolder, they will usually appear in the root folder by default. To find the root folder of an SD card, you can access it through your computer.