Every digital photo taking device stores its photo in a special folder known as DCMI. First DCMI stands for digital camera Images.
DCMI falls under DCF, a standard created by japan electronic and information technology(JEITA) IN 2003.DCF stands for Designed rule for camera file system
DCF explains that digital camera images should be stored in DCMI. and DCF is not the only standard for digital images file system but also there were other standards
Also in DCMI folder there are also subfolders. In IPhone there will be a folder such as 100APPLE while in Android devices there will be a folder like 100ANDRO. But not only this folders are found inside DCMI but sometimes other subfolders can be created. other devices create folders of the app you use like Facebook, Camera and etc.
One of the important of using this standard is that it will help photo editing and photo sharing software to locate images easily when they are needed.