The program supported viewing JPEG files with or without QuickTime installed as well as featuring slideshows (something that Apple's PictureViewer couldn't do). JPEGView was a default helper application for a number of web browsers, including both Internet Explorer and Netscape Navigator.
JPEGView allowed users to view JPEG images, whether they had QuickTime installed or not, and it also supported slideshow presentations, something that Apple's PictureViewer couldn't do.  It was commonly used as a default image viewer for web browsers like Internet Explorer and Netscape Navigator.