An optical disk is a flat, circular storage medium that uses laser technology to read and write data. Common types of optical disks include CDs, DVDs, and Blu-ray discs. These disks are typically made of plastic and have a reflective layer that allows a laser to access the data stored in tiny pits on the surface. Optical disks are widely used for storing music, movies, software, and other digital information. They are portable and can be easily duplicated, making them a popular choice for distributing media. However, with the rise of digital downloads and cloud storage, their usage has declined in recent years.