Shakes the whole frame around, like a camera nobody is holding still.
Nothing inside the picture is distorted. Every pixel moves by exactly the same amount, so the image stays intact and simply drifts, which is what separates a camera shake from a warp.
The amount it moves comes from noise rather than a regular oscillation, so the motion is unpredictable instead of a mechanical wobble. Two independent noise sources supply the horizontal and vertical drift, which stops the movement being diagonal.
The path through the noise is a closed circle, so however long you leave it running the shake returns exactly to where it started and the loop is seamless. range sets how far it travels and speed how fast, and both feed into the noise, so raising the speed changes the path as well as the pace rather than just replaying the same wobble faster.