JPEG (Joint Photographic Experts Group) is a widely used file format for storing digital photographs. It employs a lossy compression algorithm, which reduces file size by discarding some image data, resulting in a trade-off between image quality and file size.

Metadata in digital photography typically includes information such as the date and time the photograph was taken, the camera settings used, the location where the photograph was taken (if GPS data is available), and keywords or tags that describe the subject matter of the photograph. This information helps in organizing and retrieving images efficiently.

Optical discs, such as CDs, DVDs, and Blu-ray discs, are generally considered more reliable for long-term preservation of digital photographs compared to hard disk drives, solid-state drives, and magnetic tape. They are less susceptible to data corruption and degradation over time, and they can be easily stored and transported.

The rapid evolution of file formats poses a significant challenge to the long-term preservation of digital photographs. As new file formats emerge and older formats become obsolete, there is a risk that digital photographs stored in outdated formats may become inaccessible or unreadable in the future.

To ensure the long-term accessibility and integrity of digital photographs, it is important to employ a combination of strategies, including regularly migrating digital photographs to new storage media, creating multiple copies of digital photographs and storing them in different locations, and using checksums to verify the integrity of digital photographs.