The NASCAR Nationwide Series is the second highest level of professional competition in NASCAR. This level is considered to be the "minor leagues" of stockcar racing. The cars are very similar to Nextel Cup with only a few differences, such as the weight of the car.

The Nationwide Series is currently the only series of the top three to race outside the United States and the only series to have ever held points-paying international events. The season is a few races shorter, and the prize money is significantly lower.

Over the last several years, several NEXTEL Cup drivers have tried to run races in both series, using the Nationwide race as a practice. Martin Truex, Jr. won the title in 2005, and Kevin Harvick set the record for the earliest clinching of the title in NBS history in 2006. Nationwide became the title sponsor in 2008. The series was previously known as the Busch Series