http://en.wikipedia.org/wiki/Sandwich
A sandwich is a food item typically consisting of two pieces of leavened bread between which are laid one or more layers of meat, vegetable, cheese, together with optional or traditionally provided condiments, sauces, and other accompaniments. The bread is used as is, lightly buttered, or covered in a flavoured oil to enhance flavour and texture.
The term "sandwich" has been expanded�especially in the United States�to include items made with other types of bread, such as rolls and focaccia. Thus hamburgers and "subs", for example, are called "sandwiches," although not made with slices of bread from a loaf. There is also a variety of dessert called an ice cream sandwich, consisting of two square cookies (generally chocolate-flavored) with vanilla ice cream in the middle.
The nearest traditional Scandinavian equivalent is generally known elsewhere as an "open" or "open-face" sandwich, i.e. a single slice of bread with meat, fish, cheese, etc. as a topping, although the sandwich with two slices of bread has become more commonplace in recent times. This open-face variation is also prevalent in Russia, where it is known as a buterbrod (бутерброд, from the German butterbrot).
In the UK, particularly in the north of England they are known, informally, as 'butties' or 'sarnies'. This is particularly the case with sandwiches including freshly-cooked bacon and butter, though other forms of 'butty' use other ingredients and mayonnaise. A sandwich filled with chips (US: french fries) is known as a 'chip butty'. In Britain roughly 1.8 billion sandwiches are purchased outside the home every year. In French countries one might see this referred to as un Belge: a Belgian (sandwich). In Scotland, sandwiches are called 'pieces'. One Australian slang term for sandwich i