Short for "Digital Camera Images." DCIM is the standard name of the root folder digital cameras use to store digital photos. Therefore, when you connect a digital camera to your computer, the disk that appears on your desktop (Mac) or in "My Computer" (Windows) will most likely have a folder named "DCIM" inside it.
The DCIM directory is part of the DCF (Design Rule for Camera File System) developed by JEITA (Japan Electronics and Information Technology Industries Association). This file system was originally established in December 1998 and has since become the standard file system used by all digital cameras. Therefore, whenever you connect a digital camera or smartphone to your PC, your computer will look for the DCIM folder. Similarly, if you insert a memory card into a card reader connected to your computer, it will scan the memory card for a folder named "DCIM."
The DCIM folder provides a standard way for computers to recognize and import images from connected devices. For example, if your computer finds a DCIM folder on a memory card, it may automatically open your default image organization program or image importing utility. This allows all types of computers to find and import images from cameras made by different manufacturers.
While most computers include software that can automatically import all images from the DCIM folder, you can also manually browse through the images stored within the DCIM directory. However, you may have to browse through multiple subdirectories to find all the images. Additionally, your camera may save thumbnail images along with the full size images. By using a program or utility that imports digital photos, you can make sure to import all the full size images from the DCIM folder to your computer correctly.