Milling is a machining operation in which a workpiece is passed in front of a rotating cylindrical tool with multiple edges or cutting edges (in some rare cases a tool with a single cutting edge called a single profile milling cutter is used).[1]​.

With the growing use of numerical control milling machines, the milling operations that can be carried out with this type of machines are increasing, thus milling has become a versatile machining method. The development of tools has also contributed to creating new milling possibilities in addition to considerably increasing the productivity, quality and accuracy of the operations carried out.

Milling tools are characterized by their external diameter, the number of teeth, the pitch of the teeth (the pitch being understood as the distance between two consecutive teeth) and the system for fixing the milling cutter in the machine.

In universal milling machines using the appropriate accessories or in numerical control milling machines, the following milling relationship can be carried out:[2]​.