Officer of the highest rank in the diplomatic service, who represents the head of one sovereign state at the court or capital of another.
The ambassador bears credentials in the form of a sealed letter signed by the sovereign or other head of state, by which it is understood that the ambassador's negotiations will be regarded as if transacted by the head of state him- or herself.
Tradition has established that only certain states are at liberty to negotiate by means of ambassadors proper; other states negotiate by means of ministers of the second rank. An ambassador is traditionally distinguished from a minister of the second rank by the right of transacting negotiations in the head of state's presence in public and private, but in practice the head of state with whom the ambassador has transactions is attended by his or her ministers.
As representing the person of the head of state, an ambassador is entertained by the foreign government with respect. He or she is not subject to the laws of the state in which he or she resides, and the exemption also applies to the ambassador's staff, in varying degrees according to their status, but violent abuse of this privilege may lead to recall. In particular cases an ambassador may waive immunity for a member of staff. Diplomatic immunity and privileges may also be granted to people representing or connected with international organizations such as the United Nations or the European Union, and to people representing states at international conferences.