Light & Darkness
There are three levels of lighting.
Bright Light
Normal visibility. Most outdoor areas during the day and well-lit rooms.
Dim Light
Creatures and objects in dim light are concealed (DC 5 flat check to target). Torchlight at its edges, moonlight, and foggy conditions create dim light. You can’t use Seek to make something in dim light observed without a special sense.
Darkness
Creatures without darkvision or other special senses can’t see in darkness at all. A creature you can’t see is hidden or undetected to you (depending on whether you know its location).
Special Senses
Low-Light Vision: Treat dim light as bright light. You ignore the concealed condition from dim light.
Darkvision: Treat darkness as dim light (and dim light as bright light). You can see in darkness, but only in black and white.
Greater Darkvision: As darkvision, but you can also see through magical darkness.