Cutting is without any doubt the most successful application of a laser industrial processes. The first production plant for plane cutting dates back to 1972, while the first plant for cutting 3D elements appeared on the market in 1979. The total of applications covers 85-90% of the market of high power lasers, and this success is mainly related to the high contouring flexibility, the dimensional accuracy achievable, the finish quality and the limited thermal input with reduction or absence of distortions. Finally a remarkable productivity can be obtained: though the laser output may be much lower than that featured by punching, on small-medium batches laser cutting can be extremely advantageous. A continuous increase in productivity and a strong automation characterise cutting systems used in countless applications in any industrial field. Laser cutting can be performed on any kind of material and may range from 2D processing of plates and pipes, to 3D contouring, with metal sheet thickness generally included in the 1-6 mm range, though up to 25 mm may be processed. In laser cutting, the beam is directed on the material, at a power density sufficient to cause melting and keyholing on metals: material removal is obtained by a coaxial gas flow. On non-metallic materials, combustion or vaporisation cutting is used, in general with a support gas, even if, on a low thickness, gas-free cutting is possible.