F1 terms explained: a plain-English glossary
Just got into Formula 1? Here are the words the commentators and pit wall keep using — DRS, the undercut, parc fermé, “box box”, the flags and the tyre compounds — each defined in a sentence or two and linked to its own full explainer, grouped by where you hear them.
Aero & the car
DRS (Drag Reduction System)
A driver-operated flap in the rear wing that opens to cut drag and boost straight-line speed, allowed only when following closely in a DRS zone.
Ground effect
Downforce generated by shaping the car's floor so airflow underneath speeds up and sucks the car onto the track.
Dirty air
The turbulent, low-energy wake shed by a car in front that robs the following car of downforce and grip.
Porpoising
A rapid vertical bouncing of the car at speed, caused by ground-effect downforce repeatedly stalling and returning.
The halo
The titanium hoop around the cockpit that protects the driver's head from debris and impacts.
Degradation ("deg")
The gradual loss of tyre grip and lap time over a stint as the rubber wears and overheats.
Strategy & the pit stop
The undercut
Pitting for fresh tyres before a rival, then using the grip advantage to jump ahead once they stop.
The overcut
Staying out longer than a rival on older tyres, then using clear track to pit later and emerge ahead.
Box / "box, box"
The radio call telling a driver to come into the pits this lap; "box" comes from the German for the pit garage.
Marbles
Bits of worn tyre rubber that collect off the racing line and are very slippery to drive over.
Out-lap and in-lap
The out-lap is the lap leaving the pits on fresh tyres; the in-lap is the lap driven into the pits before a stop.
Pit window
The range of laps in which stopping makes strategic sense given tyre life and the cars nearby.
Race procedure & flags
Formation lap
The single lap the field completes behind no one to reach the grid, warming tyres and brakes before the start.
Parc fermé
The "closed park" rules that lock a car's set-up from the start of qualifying, banning most changes before the race.
Safety Car
A road car sent onto the track to lead and slow the field when there is a hazard, bunching the pack.
Virtual Safety Car (VSC)
An electronic slow-down that holds every car to a set delta time without deploying the physical Safety Car.
Yellow flag
Warns of a hazard ahead: slow down, no overtaking. Double waved yellows mean a serious hazard and be ready to stop.
Red flag
Stops the session immediately; cars return to the pits or grid because conditions are unsafe to continue.
Blue flag
Shown to a driver about to be lapped, telling them to let the faster leading car through.
Black flag
Shown with a driver's number, it orders that driver to return to the pits — they are disqualified or excluded.
Black-and-white flag
A sporting-conduct warning shown with a driver's number — effectively a yellow card for unsporting driving.
Chequered flag
The black-and-white checked flag waved at the finish line to signal the end of the session or race.
Tyres
Slick tyres
Smooth, treadless dry-weather tyres that maximise grip by putting as much rubber on the road as possible.
Intermediate tyres
Grooved green-marked tyres for a damp or drying track — the crossover between slicks and full wets.
Wet tyres
Deep-grooved blue-marked tyres for heavy rain, designed to clear standing water and resist aquaplaning.
Tyre compounds (soft, medium, hard)
The dry tyre range from soft (fastest, wears quickest) to hard (most durable, less grip), chosen to suit the track.
The C-range (C1–C5)
The tyre supplier's full library of dry compounds, from the hardest (C1) to the softest (C5), from which three are picked per race.
Common questions
What is DRS in F1?
A driver-operated flap in the rear wing that opens to cut drag and boost straight-line speed, allowed only when following closely in a DRS zone. Read the full definition →
What is the undercut in F1?
Pitting for fresh tyres before a rival, then using the grip advantage to jump ahead once they stop. Read the full definition →
What does “box box” mean in F1?
The radio call telling a driver to come into the pits this lap; "box" comes from the German for the pit garage. Read the full definition →
What does parc fermé mean in F1?
The "closed park" rules that lock a car's set-up from the start of qualifying, banning most changes before the race. Read the full definition →
What are marbles in F1?
Bits of worn tyre rubber that collect off the racing line and are very slippery to drive over. Read the full definition →
What does a blue flag mean in F1?
Shown to a driver about to be lapped, telling them to let the faster leading car through. Read the full definition →
What do the soft, medium and hard tyres mean in F1?
The dry tyre range from soft (fastest, wears quickest) to hard (most durable, less grip), chosen to suit the track. Read the full definition →
Know the lingo — now catch it live. See when practice, qualifying and the race start for the United States GP in your timezone, or browse the full 2026 F1 schedule.
Definitions are written in plain language from the current F1 sporting rules and common usage, and are current as of 14 August 2026. Unofficial; not affiliated with Formula 1.