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 and file structure of the original disc, making it easy to store and share. ISO files are commonly used for software distribution, allowing users to download and install programs without needing physical media. To use an ISO file, you can either burn it to a disc or mount it as a virtual drive on your computer. This allows you to access the contents just like you would with a physical disc, making it a convenient option for software installation and backup.