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Definition: storage vs. memory


Storage and memory are the two major holding areas in a computer, tablet or smartphone. In the past, they were identified and referenced correctly, but today "memory" may refer to either one.

Storage Is "Non-Volatile"
Storage comprises hard drives, solid state drives, etc., which hold programs and data. The primary attribute of storage is that it retains its content when the power is turned off.

Memory (RAM) Is "Volatile"
Memory is made up of "random access memory" (RAM) chips, which is often upgradable by the user in a desktop computer but not in a phone or tablet. In contrast to storage, memory (RAM) loses all of its content when the power is turned off.

From Storage to RAM and Back Again
When an application is run, the software and data are copied from storage to memory (RAM), and memory is where all calculating and comparing take place. Updated data may then be copied back to storage. See byte addressable.

Why the Confusion?
The problem with these terms is that many storage devices today use "flash memory" chips (see below). Consequently, people think storage and memory are the same. To avoid confusion, refer to "storage" and "RAM" rather than storage and memory. For more details, see storage, memory and storage memory.

  STORAGE DEVICES (Non-Volatile)

  hard drive        (magnetic disk)

  solid state drive (flash memory)

  USB drive         (flash memory)

  SD Card           (flash memory)

  CompactFlash      (flash memory)

  CD-R              (optical disc)

  DVD-R             (optical disc)

  DVD-RAM           (optical disc)

  magnetic tape     (tape cartridge)


  MEMORY CHIPS (Volatile)

  dynamic RAM       (DRAM chips)

  static RAM        (SRAM chips)





The Traditional Terminology
This Engadget blog described a Kindle tablet using the storage/memory definitions that have been used for decades.






They're All Chips
RAM chips (top) and storage chips (bottom) may look alike, but RAM is faster and volatile, while storage is slower and non-volatile. The USB and CompactFlash cases were removed for this photo. See memory module, USB drive and CompactFlash.










Memory Is Not Storage
These are all storage products, but because "memory" implies permanence to non-technical people, the word is used for storage by countless vendors, big and small.






Storage-Memory Hierarchy
To learn how memory and disk caches work, see cache. SSDs are faster storage than hard disks (see solid state drive).