What’s that? The terminology of graphic design.

.jpg (ja'peg') Joint Photographic Experts Group -graphics, file format
A JPEG (or JPG) file is created by choosing from a range of compression algorithms that trade image quality for size. The JPEG format is one of the image file formats supported by browsers. In addition to its wide use as a digital format for web images, .jpg files are commonly used to package commercial stock photos.