Definition: storage vs. memory

Storage and memory are the two major holding areas for programs and data in a computer, tablet or smartphone, and their interplay is the fundamental architecture of computer processing. Unfortunately, the term memory may refer to storage or memory, which only adds confusion for people learning about computers.

Storage Is "Non-Volatile"
Storage comprises hard drives and solid state drives (SSDs), which hold programs and data. The primary attribute of storage is that it retains its content when the power is turned off. USB drives and optical discs are also storage.

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

To cover all bases (and add confusion), there actually are RAM chips that are non-volatile. They serve as both storage and RAM in remote sensors and similar devices but not as the main memory in computers, phones and tablets because they are more costly (see non-volatile memory).

From Storage to Memory and Back Again
When an application is run, the software and data are copied from storage to memory (read storage; write memory). The software instructions are read from memory and executed, and the data are processed in both the CPU and memory. The updated data in memory may be displayed or printed and then read from memory and written to storage. See 3 C's and byte addressable.

Why the Confusion?
Solid state storage (SSDs and USB drives) uses "flash memory chips," a poorly conceived name for storage chips because it helps to confuse the distinction between storage and random access memory (RAM). Imagine if the brake and accelerator in a car were transposed all the time. Consequently, the average consumer may never really know that storage and memory are not the same. For more details, see storage and memory.

Disk Memory in 2024!

The term "disk memory" only adds confusion for anyone learning the field, yet this is common; witness these search results.

  STORAGE DEVICES (Non-Volatile)

  Device          Type
  hard drive      magnetic disk
  SSD             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)

  Type            Chip Type
  dynamic RAM     DRAM chips
  static RAM      SRAM chips

Correct Usage

These examples describe storage and memory correctly, from top to bottom: Chromebook Specs (see eMMC); Lenovo laptop; Apple iMac.

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.

Incorrect Usage

These examples reference storage, not memory. The problem is that "memory" implies permanence to non-technical people, but the word is used for storage by vendors, big and small.

Storage-Memory Hierarchy

To learn how memory and disk caches work, see cache. SSDs provide faster storage retrieval than hard disks (see SSD and hard disk).

Even in the Stone Age!

People have been mixing up storage and memory for millions of years!