What's a Temporary Flight Restriction?
A TFR is a temporary flight restriction. It's a FAA mandate, issued as an NOTAM, that prohibits aircraft from flying over a particular location. TFRs are often implemented for national security reasons, such as those instituted for Presidential or VIP movement. They're also activated to protect people on the ground during large events, such as over a stadium during a Super Bowl or around Disney World.
One of the most famous TFRs is around Washington, D.C. It's been in place since September 11th, 2001 to protect the White House and government buildings, and it's not all that temporary. (In fact, many industry players are demanding that this airspace is classified differently because of this reason.)
TFRs prohibit most all aircraft from operating inside of the designated restricted area for a specified amount of time. They often cover an area with a 2-mile radius to a 30-mile radius but vary in size to suit the purpose. They can be as temporary as a few hours, or they could be in place for years. The only aircraft allowed into a TFR are those approved to do so ahead of time by the FAA, and often include military or law enforcement aircraft.
TFRs are not depicted on charts, but pilots can obtain information about NOTAMs and TFRs via a flight service specialist over the phone or on the FAA's TFR website.
Pilots should always obtain this information before flying to avoid inadvertently entering a TFR area and being intercepted by a military aircraft.