EPUB is a ebook format: it packages HTML, CSS, and images in a zipped OPS container as an ISO-standardised ebook format that reflows text to fit any screen width. JPG is a image format that uses lossy DCT compression that permanently discards fine pixel detail to achieve small file sizes, ideal for photographs. This conversion changes the file's encoding, compression method, and supported feature set. Metadata such as creation date and embedded colour profiles is preserved where the target format supports it. Converting between these two formats is common when the source application does not support JPG natively or when the target platform only accepts JPG. 1converter processes this conversion server-side using open-source tools. Files are transferred over HTTPS, converted on secure cloud servers, and automatically deleted after 24 hours.