A thread is a helical notch running around a cylinder. This notch is also called a thread. A thread implements the principle of the inclined plane, whereby very high axial forces can be generated with very low tangential forces at the same time. There are internal threads and external threads. If both are to produce a force-locking connection, they must be identical and fit together. Various standards define and specify the specific characteristics of screwed connections. This ensures that screw connections from different manufacturers fit together.