When you hear "Philadelphia," the first things that come to mind might be the Liberty Bell, the theme from "Rocky" and the cheesesteak -- a delicious sandwich that is a favorite among Philadelphia natives and visitors alike.

What is a cheesesteak?
A cheesesteak is made up of thinly sliced, sauteed rib eye beef and melted cheese on a long, crusty roll. Common toppings include fried onions, hot or sweet peppers, sauteed mushrooms and ketchup. A cheesesteak hoagie is a combination of a cold hoagie (as subs are called in the Philly area), and the traditional hot cheesesteak. These have lettuce, tomato and mayonnaise.

According to Philadelphia's official tourism site, Pat Olivieri invented the cheesesteak in the 1930s. Olivieri was a hot dog vendor in south Philadelphia who, as the story goes, decided to grill some beef from the butcher and put it on an Italian roll. A cab driver caught a whiff and asked for a steak sandwich.

Word spread rapidly through the cabbie rumor mill, and drivers from all over the city soon visited Olivieri for steak sandwiches. Olivieri eventually opened up Pat's King of Steaks on 9th Street and Passyunk Avenue. Cheese was added to the mix in the '40s by Pat's manager Joe Lorenza, according to Philadelphia Magazine.

But what's an iconic figure in the City of Brotherly Love without a fierce, but friendly, rivalry?

Geno's Steaks, located on the north side of the corner of 9th and Passyunk, was started in 1966. When Joey Vento saw the name "GINO" painted on a broken door in the back of his shop, he changed the "I" to an "E," and the cheesesteak joint became Geno's. Some believe that Vento was actually the first to put the cheese in cheesesteak.

Regardless, Pat's versus Geno's is the Yankees versus Mets of the Philadelphia food scene, and you are most likely going to end up picking sides and defending your choice.

Both Pat's and Geno's are open 24 hours a day, seven days a week. Other favorite cheesesteak vendors include Tony Luke's, which, in addition to its original stand on East Oregon Avenue, has vendors in the home stadiums of the Phillies and Eagles. Jim's Steaks, which has locations in west, south and northeast Philadelphia, is another praised Philadelphia tradition.

Ordering a cheesesteak
Ordering a cheesesteak at Geno's can be a high-pressure situation for a rookie, as there is a certain no-nonsense lingo that should be applied.

For one, know exactly what you want before you reach the front of the line. Skip the small talk. Tell the cashier how many cheesesteaks you would like, your cheese of choice and if you want fried onions.

This ends up being three words: "one wiz without." (You would like one cheesesteak with Cheez Whiz but without onions.)

At Pat's, say if you want onions first, and then say the type of cheese. To order like a local, say "wit" or "wit-out," as this is how "with" and "without" sound in a Philadelphia accent.