A saw is a tool for cutting wood or other material, consisting of a serrated blade (a blade with the cutting edge dentated or toothed) and worked either by hand or by steam, water, electric or other power. The teeth of the saw are each bent to specific angle and this angle is called "set". The set of a tooth is dependent on the kind of cut the saw will be making. For example a "rip saw" has a tooth set that is similar to the angle used on a chisel. The idea is to have the teeth rip or tear the material apart.
According to Chinese tradition, the saw was invented by Lu Ban. In Greek mythology, Perdix, the nephew of Daedalos, invented the saw. In reality, metal saws likely evolved from Neolithic stone tools.