How does net shares withholding work?

Could you elaborate on the mechanics of net shares withholding? I'm particularly interested in understanding the process from the perspective of an investor. What are the steps involved in withholding shares, and how does it ultimately impact the overall shareholding structure of a company? Also, what are the key factors that determine whether or not a shareholder opts for net shares withholding? Is there a specific threshold or percentage that triggers this action? Finally, how does net shares withholding differ from other forms of share transactions, and what are the potential risks or benefits associated with it?