What's the difference between volatile and non-volatile memory?

The difference comes down to what happens when the power goes off, but that’s only part of how modern memory works.

Computer specs often use the word "memory" for several different technologies, which can make volatile and non-volatile memory sound more complicated than they are. The basic distinction is whether stored data survives when power disappears.

Volatile memory needs continuous power to retain its contents, while non-volatile memory keeps data after power is removed. That's why conventional system RAM is cleared when you shut down a computer, but files saved to an SSD are still there the next time it starts.

Volatility only describes what happens to the data when power goes away. It does not, by itself, tell you how fast a type of memory is, how much it can hold or what job it performs.

When a laptop or desktop spec lists 16GB or 32GB of RAM, it's referring to dynamic random-access memory, or DRAM. This is the computer's main working memory, which holds data while programs are running. DDR5 is one current form of DRAM in computers, while phones and other mobile devices commonly use low-power DRAM such as LPDDR5X.

Each DRAM cell stores a bit using a capacitor and a transistor. The electrical charge in the capacitor leaks over time, so DRAM has to refresh its contents repeatedly while the system is running. Once power is removed and those refreshes stop, the stored data disappears.

DRAM can come in forms other than the removable sticks commonly found in desktop PCs. AMD's Ryzen AI Max chips , for example, can work with as much as 128GB of unified memory. The underlying job is still temporary working memory, even when the physical layout looks different from a traditional DIMM (the removable stick-shaped circuit board lined with memory chips that plugs into a motherboard slot).

Static random-access memory, or SRAM, is volatile too. "Static" refers to the fact that SRAM can retain its state without the periodic refresh cycles DRAM needs, provided power is still available. SRAM uses latching circuitry with several transistors per bit, which can provide faster access than DRAM's capacitor-and-transistor cell.