Hello and welcome,
Critical operations like item distribution, level progression, and map transitions are managed on the server side. This means that the server, which is under the control of the game developers or administrators, maintains the authoritative state of the game. It processes and validates all important actions, such as the awarding of items, experience points, or the ability to move to different maps.
For example, if a player tries to give themselves a rare item, the server checks if the player has met the necessary criteria (like completing a quest or defeating a certain enemy) to legitimately obtain that item. If not, the server will deny the request. Similarly, for teleportation, the server will verify if the player has access to the destination and if the conditions for teleportation are met (like using a specific item or skill).