Describe a "hold" in air traffic control.

In air traffic control, a "hold" is a predefined pattern that includes specific legs and timing, allowing aircraft to remain in a designated area while waiting for further instructions, typically related to landing. When an aircraft is instructed to enter a hold, it follows a specified pattern, commonly a racetrack or oval shape, which involves flying a set distance in one direction before making a turn to proceed in the opposite direction. This procedure helps manage air traffic effectively, especially when the airspace around an airport is congested or when there are delays in landing due to weather or other operational factors. Aircraft in a hold will typically receive information about how long to remain in the pattern and will adhere to the specified altitude and speed until they receive clearance to proceed to their destination.