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. Various software programs, like WinRAR or Daemon Tools, can handle ISO files, making it easy to access the contents without needing the original disc.