Downforce
Downforce is aerodynamic force pushing the car into the track, which increases grip and cornering speed at the cost of straight-line speed.
It is the central trade in car setup. More wing means faster corners and a lower top speed; less wing means the opposite. Monaco and Monza sit at the two extremes, and teams bring visibly different cars to each.
Because it is generated by airflow, it scales with speed — a Formula 1 car has enormous grip at 250km/h and comparatively little at 60, which is why the slow corners are where drivers most often look untidy.