Color cycling
Animation without redrawing a single pixel — the image holds still while you rotate the values in the colour palette and let the hardware show the motion.
The trick exploits the fact that an indexed image points into a palette rather than storing colours directly. By stepping the palette registers in a loop — water flowing, lava creeping, a starfield glittering — you get motion for near-zero CPU cost, since the display re-reads the palette every frame anyway. On 1980s home computers it was often the only way to bring a still image to life.
Deluxe Paint made the feature famous in 1985 with its cycle range, and artists like Mark Ferrari pushed it to perfection in games such as Loom. In the demoscene it is the backbone of many a plasma effect: it is the palette spinning, not the pixels.