JPEG format compresses image data into a smaller file size. In theory, a JPEG file contains less data (how much depends on the specified size and compression/quality settings) than an equivalent RAW file, but is able to closely reproduce an image once fully loaded. When saving an image with photo editing software it is possible to save an image with different levels of JPEG compression. This enables you to create files that take less storage space sacrificing how well the file displays or take up more storage space to more accurately reproduce the original image.