Measured in stops, dynamic range describes how much contrast a sensor can hold. A scene with a bright window and a dim interior might span fifteen stops; a sensor that captures twelve will have to sacrifice something at one end. Blown highlights record as pure white with no information; crushed shadows record as pure black.
The asymmetry matters: highlights clip abruptly and unrecoverably, while shadows degrade gradually into noise. That is why the standard raw workflow is to expose so highlights just barely survive, then lift the shadows in post — a technique often called expose to the right, after where the histogram data sits.
Human vision vastly outperforms any single exposure, which is why a scene that looked balanced can come back as a silhouette against a white sky. Bracketing and HDR merging address this by combining exposures. Log recording addresses it for video by mapping a wide range into a flat-looking file that grades cleanly later.