Intro to Martelé, Collé, Hookstroke, Upbow staccato
Listening for the click helps improve tone, articulation and coordination.
The click means the 'attack' of a note, that is, the start of a note.
It can be heard as a strong accent (as in the martelé passage from the Allegretto of Rodes "Caprice No.9") or just as a clear articulation (as in the détaché passage from the Allegro of Rodes "Caprice No.4").
Many bowstrokes begin with noticeable clicks, including martelé, collé, accented détaché and up-bow staccato.