Optical discs are storage media that use laser technology to read and write data. Common types include CDs, DVDs, and Blu-ray discs. They are typically used for storing music, movies, software, and other digital files. The data is encoded in the form of tiny pits on the disc's surface, which a laser beam can detect. These discs are popular due to their portability and durability. They can hold varying amounts of data, with CDs storing up to 700 MB, DVDs up to 4.7 GB, and Blu-ray discs up to 25 GB or more. Optical discs are often used in home entertainment systems and computers.