Lighting affects visibility, Mob spawning, tree growth, and whether flowers and mushrooms will stay planted. Lighting can be provided by sunlight, torches, fire, lava, in-use furnaces, and certain other objects.
The following values are the brightness of the block itself. The light emitted decreases by one for each square of distance from the light source. Glass does not diminish the light that passes through it, but water or ice reduces light that passes through it by 3 (2 for passing through +1 for normal block decrease). In Minecraft's source code, the luminescences are defined using the floating point values in the third column. In a weird quirk, these floating point numbers are fractions of 16, but are multiplied by 15 to get the integer light value. This means that both 0/16 and 1/16 (0.0 and 0.0625) correspond to the integer light value 0.
|Icon||Block||Light Level||Data Value|
|End Portal Block|
|Redstone Lamp, when active|
|(Sunlight, when raining or snowing)||12||0.8125F|
|Nether Portal Block||11||0.75F|
|(Sunlight, when thundering)||10||0.6875F|
|Redstone Ore, when touched||9||0.625F|
|25px||Redstone Repeater, when active|
|Lit Redstone Torch||7||0.5F|