A Night Cache is a cache that is designed to be found at night. Finding one at night is typically easier and/or more enjoyable than finding it during the day.
Many night caches publish starting cordinates, and the geocacher must find the cache by following a series of retro-reflective trail markers that are seen easily when a flashlight/torch illuminates them in the dark, but which are difficult to find during daylight. Retro-reflective trail markers are best seen when the flashlight is held at roughly eye level. It is for this reason that headlamps are recommended. WildTech's FireTacks are excellent reflectors for night caches.
Some night caches use other techniques, including UV flourescent writing that can be seen only with a UV flashlight in the dark, or timer-controlled devices that provide the location of the next stage only at night.
For information on how to find a night cache, visit the Night Caching page