When the world descends on Louisville for the Kentucky Derby the first weekend in May, those breathtaking thoroughbreds may be first on visitors' minds, but you can bet bourbon is a close second. Bourbon's legacy is intertwined with Louisville's history going back even further than the Derby.

Pioneers in 18th-century Virginia's Kentucky County found a source of liquid income farming on the 60 acres Thomas Jefferson granted them for raising native corn – they distilled their surplus corn into whiskey. With the local limestone-filtered water and the hardwood trees for barrels, the settlers put their whiskey-making knowledge to work. No matter that the land didn't suit plowing or traditional rye – they hand-planted and raised indigenous corn. By the late 1700s this area had become part of Kentucky, and thanks to help from the French during the Revolution, one of the counties – one with a great number of the corn whiskey distilleries – was named Bourbon county (today it's a dry county – go figure).

After the steamboat's arrival in the Ohio River port town of Louisville in 1811, bourbon found new markets, particularly downriver in New Orleans. Much of the bourbon was shipped out of the original Bourbon county, and some say the Frenchmen reloading the barrels at the Falls of the Ohio (everything had to be unloaded and carried back to the ship on the other side) naturally preferred the name Bourbon.

So what exactly is bourbon, anyway? You may have heard this but it bears repeating. All bourbon is whiskey, but not all whiskey is bourbon. There are some specific requirements about proof, but the gist of it is this: Bourbon is made of more than half corn (at least 51%, though usually much more, among the rye, wheat and barley also used) and it must be aged in new charred-oak barrels. The best way to learn about bourbon, of course is to taste it, and the more open you are to learning from the local bartenders, the more they'll be happy to impart. Just don't confuse Jack Daniels Tennessee whiskey with bourbon and you'll get along fine.