Racing line
The racing line is the path through a corner that allows the highest speed — typically wide on entry, tight at the apex, wide again on exit.
It straightens the corner as much as the track width allows, because a larger radius can be taken faster. It is why a car appears to use the whole road when nobody is near it.
It is also why overtaking is hard: the defending car is on the only fast path, and passing means taking a slower one. And over a race the line becomes visibly cleaner than the rest of the track, with the discarded rubber pushed off it.