The Sprint Cup Series is the top-tier racing series in NASCAR. It was formerly known as the Strictly Stock Series and the Grand National Series. When it was sponsored by R.J. Reynolds Tobacco Company, it was known as the Winston Cup, and it was known as the Nextel Cup Series when Nextel bought the sponsorship. Nextel was bought by Sprint, which explains the last name change.
Chase for the Sprint Cup
When Nextel bought the sponsorship in 2004, they brought a new championship format, then known as the Chase for the Nextel Cup. In this format, the top twelve drivers (changed from the top ten in 2007), over the final ten races, fight for the championship. Only three drivers have won the Chase since its inception, Kurt Busch, Tony Stewart, and Jimmie Johnson. Jimmie has won it the last three years.