Volatile memory

Volatile memory is computer memory that loses stored data when power is removed. Dynamic and static random-access memory are its principal forms.

Dynamic random-access memory: Semiconductor memory that stores each bit as charge in a capacitor and must periodically refresh it. Its capacitors leak charge, so continuous power and refresh cycles preserve data.
Non-volatile memory: Computer memory that retains stored data without continuous electrical power. It differs from volatile memory precisely in retaining data after power is removed.
Computer memory hierarchy: The organization of storage technologies by speed, capacity, cost, and proximity to the processor. Volatile memory occupies the fast working-storage levels between processor registers and persistent storage.
Random-access memory: Memory that allows data at each address to be accessed directly in roughly comparable time. DRAM and SRAM are volatile forms of this addressable memory family.
Static random-access memory: Semiconductor memory that stores each bit in a bistable circuit while power is supplied. Its circuit holds data without refresh, but loses it when power stops.
Read-only memory: Memory designed primarily for reading, whose contents persist without power. Unlike volatile working memory, ROM can preserve instructions through shutdowns.
Virtual memory: A system that uses address translation and storage devices to give programs a larger address space than physical RAM. Its pages move between volatile RAM and persistent storage as active working sets change.
Capacitor: An electrical component that stores energy in an electric field between conductors. A DRAM cell uses a capacitor’s charge to represent a bit temporarily.
Memory cell: A circuit or physical element that stores one or more bits of information. Volatile memory is built from cells whose electrical states encode data.
Flash memory: Non-volatile semiconductor memory that stores data by trapping electrical charge. Flash keeps data without power, making it a common persistent-storage counterpart to RAM.

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