Light in Minecraft affects certain things, such as mob spawning and visibility. Light can be provided by Ambrosium Torches, Aether Portals, sunlight, fire, and various other sources.
Brightness[ | ]
There are 16 total light levels in integers, which are 0 to 15. Minecraft uses the light levels of blocks to calculate the brightness of a selected block.
If the light level is 0, a block will be close to black. If the light level is 15, a white block will be close to white, and a green block will be close to green.