What is shyrif?

Shyrif is the curvy part of the letter. Look at how the center of the 'S' curves to create the form of well, an 'S'. and the end of the 'y' is curled out to create the tail.

When you search in wikipedia, it says it is the "non-structural details on the ends of some of the strokes that make up letters and symbols." and I'm not sure if theres any simpler was to explain it.