What does the term "jackknifing" refer to in driving?

The term "jackknifing" specifically describes a situation in driving where the trailer of a combination vehicle, such as a truck and trailer, swings out to one side, creating an angle with the tractor unit. This often occurs when the rear wheels of the tractor or the trailer wheels lose traction, causing the trailer to pivot sideways relative to the towing vehicle. This can result from rapid braking, road conditions like ice or water, or poor handling during a turn. Understanding this maneuver is critical for commercial drivers, as jackknifing can lead to accidents and loss of control. Recognizing and preventing conditions that lead to jackknifing is essential for safe driving practices.