The Nationwide Series and Craftsman Truck Series are the two lower tiers of races, neither as popular nor as widely followed as the Sprint Cup. What makes these races events out from the more popular Sprint Cup is the addition of non-Sprint Cup drivers.
The Nationwide and Craftsman Series are a sort of minor leagues for younger or newer drivers, with the more well-known seasoned drivers often participating alongside. This has created some problems lately, as the veteran Cup drivers are dominating the lesser experienced competition.
The Sprint Cup Series (formerly called the NEXTEL Cup) is the largest and most popular of the three tiers, consisting of the most well-known races such as the Daytona 500.
The Cup Series, as its often shortened to, is a 36-race season with the last 10 races making up the "Chase for the Cup." For these last 10 races, all points totals are reset to zero, but the catch is that only the top 12 drivers in terms of points from the season up to that point are eligible to win the championship. All drivers still participate, so the field remains at 43 cars, but only the 12 highest points earners continue receiving points and are pitted against each other.