How Did it originate?
The original “Oktoberfest” occurred in Munich, on October 18, 1810: For the commemoration of their marriage, Crown Prince Ludwig (later King Ludwig I) and Princess Therese of Saxe-Hildburghausen (namesake of the Theresienwiese festival grounds) organized a great horse race (the marriage took place on October 12; the horse race on October 17 — therefore, there are different dates named as being the first Oktoberfest).
Exactly when does it take place?
Oktoberfest is a 16-day festival held each year in Munich, Germany, running from late September to early October. It is one of the most famous events in Germany and the world’s largest fair, with some six million people attending every year, and is an important part of Bavarian culture. Other cities across the world also hold Oktoberfest celebrations, modeled after the Munich event.
The Munich Oktoberfest, traditionally, takes place during the sixteen days up to and including the first Sunday in October. In 1994, the schedule was modified in response to German reunification so that if the first Sunday in October falls on the 1st or 2nd, then the festival will go on until October 3 (German Unity Day). Thus, the festival is now 17 days when the 1st Sunday is October 2 and 18 days when it is October 1. The festival is held on an area named the Theresienwiese (field, or meadow, of Therese), often called d’ Wiesn for short.
Okay, So What about the Food?
Visitors also eat huge amounts of traditional hearty fare such as Hendl (chicken), Schweinsbraten (roast pork), Haxn (knuckle of pork), Steckerlfisch (grilled fish on a stick), Würstel (sausages) along with Brezeln (Pretzel), Knödeln (potato or bread dumplings), Käsespätzle (cheese noodles), Reiberdatschi (potato pancakes), Sauerkraut or Rotkraut (red cabbage) along with such Bavarian delicacies as Obatzda (a fatty, spiced cheese-butter concoction) and Weisswurst (a white sausage).
For more about the history visit: http://en.wikipedia.org/wiki/Oktoberfest