The National Guard is a reserve military force made up of citizen-soldiers who train part-time while living ordinary lives in their home states. Unlike active-duty soldiers who work full-time for the military, many National Guard members serve one weekend per month and two weeks per year, while also holding regular jobs as teachers, mechanics, doctors, or doing many other kinds of work.

Each state and territory has its own National Guard unit, and the state's governor can call them to action during emergencies. When hurricanes flood towns, when wildfires threaten communities, or when severe storms knock out power, the National Guard often arrives to rescue people, deliver supplies, and help keep people safe. They've helped during many disasters, from Hurricane Katrina to winter blizzards.

The National Guard also serves as part of America's military when needed. The President can activate Guard units to support the regular Army or Air Force during wars or overseas missions. This dual role makes the Guard unique: they serve both their home state and the entire nation.

The Guard traces its history back to colonial militias in the 1600s, making it older than the United States itself. These early militias were groups of ordinary citizens who trained together to defend their communities, much like the National Guard does today.