The metal stringed Mandolin took form in Italy sometime in the early 18th century. Today, there are many types of mandolins, but typically you will encounter four standard styles. The Neapolitan, Carved top, Flat-Backed and the solid body electric mandolins.
Neapolitan or Round-Backed Mandolin: This mandolin is very distinctive looking as it has a round back resembling a bowl. This mandolin also features a flat top and an oval sound hole. Older versions of this instrument will sometimes have what is known as a “bent sound table” which is a bent or angled top. This design was thought to help alleviate pressure from the strings.
Flat-Backed Mandolin: These mandolins developed in Europe in the 1850’s. They are constructed of thin sheets of wood with internal bracing (just like a guitar). Typically they sport an oval sound hole. These mandolins are used for a wide variety of music and go by many names: Portuguese, Celtic, Bandolim, Army-Navy, Flatiron, and the Pancake Mandolins.
Carved-Top Mandolin: These mandolins are based on the principles of violin construction. The backs and tops are carved out of the wood making them arched in shape. Orville Gibson is the person responsible for pioneering these designs and presenting them to the world. His Gibson A-4 (1905) and F-4 (1910) were revolutionary instruments and have forever changed mandolin design.
The Electric Mandolin: This mandolin is tuned and played exactly as a conventional acoustic mandolin, but draws inspiration from the electric guitar. Like the electric guitar, it has a solid body fitted with magnetic pickups. Some models are strung as usual with the eight double strings, but there are also four (single) stringed versions as well.
The Mandolin Slicer: Although this food processing device has "Mandolin" in it's name, keep your fingers away. It does, however, slice potatoes really well so one can make delicious homemade chips.