Official Minecraft: Player's Handbook

Minecraft is a game devoid of quests and guided adventures. The world of Minecraft exists for you to build it and transform it into anything and everything imaginable. It operates on a 20 minute day/night cycle, with 10 minutes of daytime, 1.5 minutes at sunset and sunrise, and 7 minutes of nighttime. During nighttime, the world is covered in darkness, allowing hostile mobs to spawn on the surface.