Stabilize - Especially when cooking with a round-bottomed wok, a wok ring can add much-needed stability. It cradles the bottom of the wok to keep it from rolling across your cooktop.
Direct heat - Since stir-fry and other forms of wok cooking require high heat, finding a way to direct your flame can make a big difference. A wok ring helps trap and direct heat rather than letting it escape out the sides of your pan.
Protect - The metal grates on gas stovetops can stabilize a wok, but they also scratch it, leaving it open to rust. A wok ring helps protect your pan from wear and tear, ensuring that it lasts longer.