Oversteer
Oversteer is when the rear tires lose grip before the fronts, so the car turns more than you asked and the back swings outward.
Also called: loose, tail-happy
In oversteer, the rear tires reach the limit of grip first. The tail starts to swing out, the car rotates faster than the steering asks for, and if nothing changes, it spins. From the seat, it feels like the car is pivoting around your hips and the view through the windshield moves sideways.
It can come from many sources: too much throttle in a rear-drive car, an abrupt lift mid-corner, braking too hard while turning, or a setup that leaves the rear lacking grip. A small amount of oversteer is a powerful tool for rotating the car; too much is a spin.
Catch it by looking where you want to go and applying smooth, quick counter-steer in the direction of the slide. Avoid stabbing the brakes or slamming the throttle shut. If it goes beyond what you can catch, use the spin procedure: both feet in. Most instructors would rather you spin safely than wrestle a car into a wall.
Understanding oversteer and its triggers helps you prevent spins, the most common cause of incidents at track days.
The rear tires run out of grip first. The car rotates more than you asked. Look where you want to go, steer smoothly into the slide and avoid sudden lifts or stabs of the brake.