In vanilla Minecraft, darkness is represented by black or dark blue overlays on textures. A Fullbright pack replaces these overlays with fully transparent or solid bright white/gray blocks of color. The result is that every block—whether in a cave, the Nether, or the deep ocean—appears as if it is under direct noon sunlight.
The pack not only brightens the game but also adds a layer of vibrancy to the textures, making the Minecraft world look more alive and visually appealing. fullbright texture pack 1122 link
: Permanently adjusts light levels so you can see clearly in caves, underwater, and throughout the Nether and End dimensions. In vanilla Minecraft, darkness is represented by black