A Native American reservation is an area of land held and governed by a U.S. federal government-recognized Native American tribal nation, whose government is semi-sovereign, subject to regulations passed by the United States Congress and administered by the United States Bureau of Indian Affairs, and not to the U.S. state government in which it is located. The term "reservation" is a legal designation that comes from the conception of the Native American nations as independent sovereigns at the time the U.S. Constitution was ratified. Early peace treaties, often signed under conditions of duress or fraud, in which Native American nations surrendered large portions of their land to the United States, designated parcels which the nations, as sovereigns, "reserved" to themselves, and those parcels came to be called "reservations".

There are approximately 326 Indian land areas in the U.S. administered as federal Indian reservations (i.e., reservations, pueblos, rancherias, missions, villages, communities, etc.) . The largest is the 16 million-acre Navajo Nation Reservation located in Arizona, New Mexico, and Utah, while the smallest is a 1.32-acre parcel in California where the Pit River Tribe’s cemetery is located. Many of the smaller reservations are less than 1,000 acres. Some reservations are the remnants of a tribe’s original land base, while others were created by the federal government for the resettling of Indian people forcibly relocated from their homelands.

Federal Indian reservations are generally exempt from state jurisdiction, including taxation, except when Congress specifically authorizes such jurisdiction.