A CD-R, or Compact Disc-Recordable, is a type of optical disc that allows users to write data onto it once. Unlike standard CDs, which are pre-recorded, a CD-R can be used to store music, documents, or other files. Once the data is written, it cannot be erased or modified, making it a reliable option for archiving information. CD-Rs are commonly used for personal and professional purposes, such as creating music albums or backing up important files. They typically hold up to 700 MB of data or about 80 minutes of audio. CD-Rs are compatible with most CD players and computers, making them a versatile storage solution.