If we use a term you don't recognise, it should be here. If it isn't, tell us and we'll add it.
- Active aero
- Wing elements that change shape during a lap to reduce drag on straights, then return to high-downforce shape for corners. Standard from 2026.
- Brier score
- A scoring rule for probabilistic predictions: the mean squared error between predicted probability and actual outcome (0 or 1). Lower is better. We grade our race-by-race predictions in Brier.
- Calibration
- A 70% prediction should be right 70% of the time. Calibration measures how close model probabilities match reality across many predictions. See /charts.
- Compound (tyre)
- Pirelli supplies six dry compounds, labelled C1 (hardest) to C6 (softest). The three chosen for a race weekend are nominally hard, medium and soft.
- DRS
- Drag Reduction System. Driver-actuated flap that opens the rear wing on designated straights. Retained in 2026 but supplanted in importance by active aero.
- Elo
- A pairwise rating system originally from chess. We use a modified Elo for driver and team head-to-heads — each race result updates both participants. See /ratings.
- ERS
- Energy Recovery System. The hybrid component of the power unit. From 2026, accounts for ~50% of power output, up from ~20%.
- FastF1
- Open-source Python library that exposes F1 live timing, lap times, weather and tyre data. One of our two main data feeds.
- FCY
- Full Course Yellow. A neutralisation phase where drivers must reduce to a delta laptime, without a safety car deployment.
- Gap (championship)
- Points difference between two drivers or teams. We track the running gap, and project the final gap based on race-by-race model output.
- Hierarchical model
- A Bayesian model where parameters are themselves drawn from higher-level distributions. Lets us pool information across drivers, teams and circuits.
- Lap delta
- Difference between two lap times, usually in seconds. We use delta-to-fastest, delta-to-teammate, and delta-to-pole interchangeably with the context clarified.
- MGU-K / MGU-H
- Motor Generator Units. The K (kinetic) recovers energy under braking; the H (heat) recovered energy from the turbo. MGU-H removed for 2026; only MGU-K remains.
- Parc Fermé
- The condition entered when a car finishes qualifying. The setup is locked; only a strict list of changes is permitted before the race.
- Posterior
- In Bayesian inference, the updated probability distribution after observing data. Our predictions come out of a posterior, not a single point estimate.
- Q1 / Q2 / Q3
- The three knockout qualifying segments. Introduced in 2006; the modern format we use to anchor driver ratings begins in 2003.
- Sprint
- Short race held on Saturday at six selected weekends. Awards 8-7-6-5-4-3-2-1 points for top eight.
- VSC
- Virtual Safety Car. See FCY — the same idea by a different name in different eras of the regulations.