The National Animal Identification System (NAIS) is a program of the United States Department of Agriculture (USDA) that is administered by the Animal and Plant Health Inspection Service (APHIS), often in partnership with state departments of agriculture.

Its primary purpose is to be able to track the location of specific species of domestic animals, especially if a disease outbreak occurs.

The primary components of the program are:
1) Premises identification: Each premises is identified with a unique Premises Identification Number (PIN). Information such as the premises's owner, type of operation, and geolocation are recorded in a national database. Knowing where animals were born and where they were moved will assist animal health officials in the event of an animal health outbreak.

2) Animal identification: To track animals through their entire lifecycles, a standard identification system is required. Animals are identified with a unique Animal Identification Number (AIN), or, if they are managed and moved through their lifecycle as a group, they are assigned a Group/Lot Identification Number (GIN).

3) Animal tracking: The AIN and GIN are related to a PIN to record every premises where an animal or group of animals has been housed as they move through the various stages of production.

For more information, see: Animal Plant and Health Inspection Service: NAIS.