IMSA runs several championships at once, because each class races for its own crown. At every round, finishers score championship points by class toward the season-long drivers', teams' and manufacturers' titles — the higher you finish in your class, the more points you bank. There is no single combined order; the fight in GTP is scored separately from those in LMP2, GTD Pro and GTD.
Layered on top is the Michelin Endurance Cup, a championship-within-a-championship contested only at the five longest races: the Rolex 24 At Daytona, 12 Hours of Sebring, Six Hours of The Glen, the six-hour round at Road America and Petit Le Mans.
Its twist is when points are scored. Rather than paying out only at the chequered flag, the Endurance Cup banks points at intervals through each race — for example, at the 6-, 12- and 18-hour marks and the finish of the Rolex 24. That rewards sustained pace and reliability across the full distance, not just a strong final stint. See also how an IMSA race weekend works.