To understand exactly what makes up a RAW file, you first need to understand how most current digital cameras work. Sensors create an image from millions of light-sensing areas of a chip. Most sensors actually only record in greyscale values and then use filters and color schemes such as the Bayer Pattern (invented by a Kodiak scientist Dr. Bayer in the 1980's) to determine the colors. There are usually three different colors: red, green, and blue.
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RAW files are usually proprietary to the camera manufacturer and sometimes a specific camera model. That means that only the camera that captures the picture can understand the information collected on the sensors. The settings associated with them, such as the aperture, shutter speed, white balance, contrast, sharpening, and saturation values are not applied; they are stored for later use. RAW images are primarily used by professional photographers who require complete control over their image.
