See memory for the mechanism in living things.
Electronic computers use a wide range of memory technologies for high-speed computing, as well as mass storage with greater capacity but slower access times. The primary electronic memories may be both readable and writable (random access memory (RAM)), write-once-read-many (WORM) of various types, or forms that can be read freely but require special procedures to change.
RAM is normally addressed by a numeric memory address; think telephone number. A different alternative is content addressable memory (CAM), again with different physical types and capabilities.