Scissors are hand-operated cutting tools consisting of two blades, each sharpened on one side, joined at a pivot that acts as a fulcrum. Scissors cut material by applying local shear stress that exceeds the material's shear strength at the cutting location. The earliest known scissors appeared in Mesopotamia some 3,000 to 4,000 years ago; they were of the "spring" type, the blades being connected at the handle end by a thin, flexible strip of metal. These spring scissors continued in use in Europe until the 16th century, but were then superseded by scissors with a central pivot, which had been invented by the Romans around AD 100. Modern scissors, with holes in the handles for finger control, come in a range of types designed for various purposes, with left-handed scissors being designed for use with the left hand. Larger tools tend to be called "shears".Photograph credit: Chris Woodrich