Unlike a Freeze-Out tournament in which you are eliminated once you've lost your chips, a Rebuy tournament allows you the opportunity to purchase more chips for an allotted time.
There is generally a rebuy period for the first hour of the tournament although it may vary. Players may rebuy chips should they have lost all their chips or have less than they did when the tournament originally started. Eligibility of rebuys may vary depending on the tournament.
Re-buy tournaments typically have an add-on period at the end of the rebuy stage. Although this may vary, players may usually add on for the same amount of chips they started with. Generally add-ons are offered to everybody regardless of size of stack. Once the add-on period is over players can no longer buy-in or rebuy into the event.
The final prize pool will remain undetermined until all rebuy and add-ons are complete. Please read the rebuy rules of the tournament in the "Tournament Lobby" before playing as rules may vary depending on the tournament.