The most fundamental tasks of adventuring — noticing danger, finding hidden objects, hitting an enemy in combat, and targeting a spell, to name just a few — rely heavily on a character's ability to see. Darkness and other effects that obscure vision can prove a significant hindrance. Below are the details on obscurity, light, and the different types of visions and senses.
OBSCURITY
An area can be clear, lightly obscured, or heavily obscured.
CLEAR
An area with no visual impairment and no effect on vision or senses.
LIGHTLY OBSCURED
A lightly obscured area, such as dim light, patchy fog, or moderate foliage, creatures have disadvantage on Wisdom (Perception) checks that rely on sight, this incurs a -5 to passive perception scores.
HEAVILY OBSCURED
A heavily obsured area—such as darkness, opaque fog, or dense foliage—blocks vision entirely. A creature effectively suffers from the blinded condition when trying to see something in that area.
LIGHTS
The presence or absence of light in an environment creates three categories of illumination: bright light, dim light, and darkness.
BRIGHT LIGHT
Lets most creatures see normally. Even gloomy days provide bright light, as do torches, lanterns, fires, and other sources of illumination within a specific radius.
DIM LIGHT
Also called shadows, creates a lightly obscured area. An area of dim light is usually a boundary between a source of bright light, such as a torch, and surrounding darkness. The soft light of twilight and dawn also counts as dim light. A particularly brilliant full moon might bathe the land in dim light.
DARKNSS
Darkness creates a heavily obscured area. Characters face darkness outdoors at night (even most moonlit nights), within the confines of an unlit dungeon or a subterranean vault, or in an area of magical darkness.
VISION TYPES
BLINDSIGHT
A creature with BLINDSIGHT can perceive its surroundings without relying on sight, within a specific radius. Creatures without eyes, such as oozes, and creatures with echolocation or heightened senses, such as bats and true dragons, have this sense.
DARKVISION
A creature with DARKVISION can see in dim light as if it were bright light and in darkness as if it were dim light, so areas of darkness are only LIGHTLY OBSCURED as far as that creature is concerned. However, the creature can’t discern color in that darkness, only shades of gray.
TRUESIGHT
A creature with TRUESIGHT can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceives the original form of a shapechanger or a creature that is transformed by magic. Furthermore, the creature can see into the Ethereal Plane.
