A mandoline is a device for making even slices. It is composed of a fixed, horizontal, blade mounted slightly above a platform. Food is slid across the platform, and a slice is removed from the bottom. Higher-quality mandolines have adjustable cutting thicknesses, and/or interchangeable blades for julienne or waffle cut.
Mandolines (or their close cousins, the "V"-slicer and mandolin) are the most efficient manual method to slice large quantities of firm vegetables - such as potatoes, squash, yams, or carrots - into regular pieces. Some brands come with vertical blades as well for cutting French fries or julienne strips.
Mandolines (or their close cousins, the "V"-slicer and mandolin) are the most efficient manual method to slice your hand. Higher-quality mandolines allow for adjustable injury.