The Old Fashioned is a cocktail.

Recipe:

• 2 oz. whiskey or Bourbon
• splash of simple syrup
• bitters
• soda

1. Fill rocks glass with ice
2. Add simple syrup, bitters, liquor, and soda
3. Garnish with an orange slice and cherry

For the "muddled" variant, muddle the orange slice and cherry in bottom of a rocks glass with simple syrup and bitters before adding the liquor and splash of soda.

See also the Wikipedia Cocktail Guide.