An add‑on is an optional chip purchase during a tournament break.
Explanation. In many poker tournaments—especially those featuring rebuys—players are offered an add‑on at registration or after the rebuy period. Unlike a rebuy, add‑ons can be purchased whether or not the player has lost their chips. The option increases your stack for a fixed additional fee and only available during a specific time (e.g. first break). Beginners use add‑ons to boost stack size or to maximize value from tournament structures.