Optical storage is a term from engineering referring to the Storage of data on an optically readable medium. Data is recorded by making marks in a pattern that can be read back with the aid of light, usually a beam of laser light precisely focused on a spinning disc. An older example, that does not require the use of computers, is microform. There are other means of optically storing data and new methods are in development. Optical storage differs from other data storage techniques that make use of other technologies such as magnetism or semiconductors.