A Caesar salad is a salad made classically with romaine lettuce, croutons, grated Parmesan cheese, and a vinaigrette dressing. This basic salad is immensely popular among a diverse cross-section of humanity, and a wide number of variations on the basic Caesar are served and sold all over the world. Many restaurants have a Caesar of some form or another on their menus, and it is often prepared at home as well, sometimes with additional ingredients like grilled chicken or anchovies.
Credit for the invention of the Caesar salad is generally given to Caesar and Alex Cardini, brothers who ran a restaurant in Mexico during the Prohibition era. According to popular mythology, when a Fourth of July rush wiped out their kitchen supplies, the brothers combined the ingredients on hand, tossing them tableside for extra flair, and the Caesar salad was born. This event took place around 1924, and since no earlier claims for the invention have been put forward, it is probably safe to assume that credit should indeed rest with the Cardinis.
According to Caesar Cardini, the dressing includes mustard, garlic, olive oil, salt, pepper, wine vinegar, lime or lemon juice, Worcestershire sauce, and a raw or coddled egg. Ideally the garlic should be pressed in the olive oil and allowed to soak, creating a stronger flavor, and Cardini disapproves of the addition of anchovies, claiming that the Worcestershire sauce provides the hint of fishy flavor which is needed.
The romaine leaves in a Caesar salad are traditionally left whole, as the salad is meant to be eaten with the fingers, although many diners are not aware of this. The marriage of crisp, cool romaine, crunchy croutons, salty fresh-ground Parmesan, and the tangy dressing is viewed by some to be one of the finest culinary experiences in the world. Alas, the pure Caesar has many imitators, including versions made with other cheeses, cut lettuce, various meats, and adulterations like parsley.
Some people choose to omit the raw egg in Caesar salad dressing, due to concerns about food-borne illness such as salmonella. It is possible to use pasteurized egg products to create the desired texture and flavor without the danger, and these products are used in commercial Caesar dressings, which are available at many markets. You can also make the dressing yourself, of course, with or without raw egg; you may find that a fresh, home-made dressing transforms the flavor of the salad, explaining why it has become so popular with such simple ingredients.