Random-access memory (RAM) refers to a storage technology that allows you to read and write data as many times as needed. Contrast this to ROM which allows data to be written once after which it permits only reading. RAM is typically erased when a computer is shut down, though some RAM chips maintain data indefinitely without electrical power. Technically, RAM devices are not limited to memory chips, and random-access memory as a storage format is not limited to use as working memory. In a broad sense, modern storage devices for long-term or secondary storage, including magnetic media and laser-readable CDs and DVDs, are forms of random-access memory.