A more thorough explanation:

Definition: Secret diplomacy is a type of diplomacy where negotiations between national governments are carried out behind closed doors, without the knowledge of the public or interested observers.

For example, if two countries are in a dispute and they want to resolve it without the interference of other countries or the media, they may engage in secret diplomacy. This type of diplomacy is also known as quiet diplomacy.

Another example of secret diplomacy is when a mediator is used to negotiate the settlement of a lawsuit. The mediator travels back and forth between different rooms, one of which is assigned to each side's decision-makers and counsel. The mediator relays offers and demands between the rooms and seeks to reach an agreed resolution of the case. The mediator does not bring the parties together in the same room.

Secret diplomacy can be controversial because it can lead to decisions being made without the input or knowledge of the public. However, it can also be useful in resolving sensitive issues that require discretion.