What is the most valuable private company in the world?

Could you please elaborate on what criteria are typically used to determine the most valuable private company in the world? Are we looking at revenue, profitability, or market valuation? Additionally, are there any specific industries that tend to dominate this ranking, and how does the current global economic climate affect the valuation of these companies? Furthermore, are there any up-and-coming private companies that have the potential to surpass the current leaders in terms of value?