The Nether is a hell-like dimension accessible only by entering a nether Portal from the Overworld. It home to several hazards, including flames, widespread standing and flowing lava, and Nether-exclusive mobs, as well as exclusive items and blocks. Location in The Nether correlate to Overworld coordinates, but Nether distances are scaled down. Therefore traveling one block in the Nether means traveling eight blocks in the Overworld. This fact can be used as an Overworld travel shortcut, although the Nether is significantly more hazardous and has more complex terrain, making navigation difficult. Functioning as a second map in a player's world, when entered chunks from the Overworld map are unloaded and Nether chunks load instead. Terrain generates infinitely in the Nether, and if the player dies down there they will respawn in the Overworld while all surviving inventory items remain under.
Terrain is largely composed of Netherrack that forms complex platforms and niches, with frequent lava pools, lavafalls and streams, and a lava ocean as its floor. It is essentially a complex cave that is hazardous and horizontally infinite. Lava also flows more quickly in the Nether, and bedrock comprises the very top and bottom layers. Glowstone clusters hang from ceilings and mushrooms grow abundantly on the ground. There are patches of gravel and soul sand, as well as random fires. Small tunnels form in the Netherrack, which contain random Nether Quartz deposits, but there are no hidden caverns to explore. Zombie Pigmen are common and Ghasts can also spawn in any 5x5x5 area. Nether Fortresses, the Nether's only naturally occurring structures, are where the rest of the Nether mobs spawn, and these can provide important dropped items but present some hazards. They are also the only place where Nether Wart can be found.
The Nether has no day/night cycle and no weather. The only natural sources of light are fire, lava, portals and glowstone. A dim ambient light can be seen throughout the Nether which is actually what light level 0 looks like. Plants that usually require a minimum light level, such as flowers and Nether wart, can survive in this light level in the Nether. However, this doesn't work below natural veins of glowstone or below lava source blocks that appear naturally in cave walls. Plants at any level below these formations, even if separated by other terrain, will uproot if not adequately lit.