1. teeth, through the threads on the axis of the profile, thread profile called profile. Angle between two adjacent teeth the side known as the thread form angle. General purpose screw threads commonly used teeth type triangle, tooth type angle of 60 °.
2. diameter, diameter major diameter of the thread, trails, paths, is the nominal diameter for threaded, representative of the nominal diameter is the diameter of the thread size. Nominal diameter is the diameter of the thread.
3. rotation direction, along the axis direction, rotate screw clockwise right or left-handed thread, counter clockwise thread called a left-hand thread.
4. line, form the spirals of the thread called line number. Be divided into single and multi thread, thread in a perpendicular to the axes of the cross section is uniformly distributed.
5. pitch, two adjacent teeth on the diameter corresponds to the distance point to the axis is called pitch. On the same Helix, two adjacent teeth on the diameter corresponds to the distance point to the axis is called pitch.