An ISO file is a digital copy of an entire optical disc, such as a CD, DVD, or Blu-ray. It contains all the data from the disc, including the file system and structure, allowing users to replicate the original disc's content without needing the physical media. ISO files are commonly used for software distribution, backups, and archiving. To use an ISO file, it can be mounted as a virtual drive or burned onto a physical disc. Many operating systems and software applications, like Windows and macOS, support ISO files, making it easy to access and install programs or media contained within them.