An NRG file is a proprietary disc image format created by Nero AG, primarily used with their Nero Burning ROM software. It's essentially a complete copy of a CD, DVD, or Blu-ray disc, including all the data, file system information, and structure. This allows users to create exact replicas of their discs for backup purposes, archiving, or distribution. NRG files can contain various types of data, such as audio, video, software, or documents. They are often used to create bootable discs, which are essential for installing operating systems or running diagnostic tools. While NRG is a proprietary format, several other software applications besides Nero Burning ROM can open and extract the contents of NRG files. However, compatibility and support may vary depending on the specific software and the complexity of the NRG image. NRG files are not as universally supported as ISO images, which are an open standard, but they remain a popular choice for users familiar with Nero software.