With thousands of types of wine grapes in existence,Sterling Preston understanding wine can be difficult, and knowing how to order it can be intimidating.

That reality led Oklahoman Randa Warren down a path that would eventually gain her the title of master sommelier. But the knowledge required of those who pass The Court of Master Sommeliers' exam for its highest title is extensive. When she passed the exam in 2007, it was only being given once a year. It took Warren five attempts to clear all three sections — theory, tasting and service.