Common applications for night vision include:
• Military
• Law enforcement
• Hunting
• Wildlife observation
• Surveillance
• Security
• Navigation
• Hidden-object detection
• Entertainment
The original purpose of night vision was to locate enemy targets at night. It is still used extensively by the military for that purpose, as well as for navigation, surveillance and targeting. Police and security often use both thermal-imaging and image-enhancement technology, particularly for surveillance. Hunters and nature enthusiasts use NVDs to maneuver through the woods at night.
Detectives and private investigators use night vision to watch people they are assigned to track. Many businesses have permanently-mounted cameras equipped with night vision to monitor the surroundings.
Source
http://science.howstuffworks.com/nightvision.htm