In many simulators, including Pickaxe Simulator, rebirth is a soft reset that trades your current progress for permanent multipliers or rebirth tokens. After a rebirth you start again from early gear, but you earn coins and power much faster than on your first run. The Upgrades list even has a dedicated "More Rebirths" track (29 tiers) that raises how many tokens you pocket per reset, so the system is meant to be looped.
Exact details can vary by update, but rebirth systems generally follow the same pattern. Knowing what you keep makes it easier to accept resetting your visible progress. In Pickaxe Simulator you keep anything tied to Robux purchases (gamepasses, Robux pickaxes/miners), permanent upgrades bought with gems, and your rebirth multipliers, while coins/pickaxes/miners tied to the current run reset.
A simple way to use the Rebirth System well is to wait until your progress slows down so much that the next upgrades feel painfully expensive. At that point, starting over with multipliers is often faster than grinding forward with your current stats. Use real thresholds from the pickaxe list to guide you: once you reach Glacier Core (30M coins) or Gemstone Smasher (750M coins) and upgrades begin to take hours, bank a few million extra coins, buy any pending gem upgrades, and hit the rebirth button.
You do not need to rebirth during your very first hour, but once you understand the core loop, using the Rebirth System smartly will speed up every future play session. Keep a short checklist that references the official world and egg order so you never have to think during the early grind.