Learn in the textbookBasics of Semiconductor Memory — RAM, ROM, and Volatility
DefinitionVolatile memory (揮発性メモリ) is memory whose stored contents disappear once the power supply stops.
ExplanationIt keeps its contents by drawing power continuously, so the data is lost when the power goes off. RAM has this property, which is why unsaved work in progress disappears in a power outage.
AnalogyIt is like a balloon you keep blowing into. Stop blowing and take your mouth away, and the air quickly escapes.
Memory hookThe Japanese word 揮発 means evaporating away, as alcohol or gasoline does. Its characters suggest contents flying off when the power is cut.