Second Secretary

Diplomatic rank is the system of professional and social rank used in the world of diplomacy and international relations. A diplomat's rank determines many ceremonial details, such as the order of precedence at official processions, table seatings at state dinners, the person to whom diplomatic credentials should be presented, and the title by which the diplomat should be addressed.

The current system of diplomatic ranks was established by the Vienna Convention on Diplomatic Relations (1961). There are three ranks, two of which remain in use:

The body of diplomats accredited to a country form the Diplomatic corps. Ambassadors have precedence over chargés, and precedence within each rank is determined by the date on which diplomatic credentials were presented. The longest-serving ambassador is the Dean of the Diplomatic Corps, who speaks for the entire diplomatic corps on matters of diplomatic privilege and protocol. In many Catholic countries, the papal nuncio is always considered the Dean of the Diplomatic Corps.

The ranks established by the Vienna Convention (1961) modify a more elaborate system of ranks that was established by the Congress of Vienna (1815):

The rank of Envoy was short for "Envoy Extraordinary and Minister Plenipotentiary", and was more commonly known as Minister. For example, the Envoy Extraordinary and Minister Plenipotentiary of the United States to the French Empire was known as the "United States Minister to France" and addressed as "Monsieur le Ministre."

An Ambassador was regarded as the personal representative of his sovereign as well as his government. Only major monarchies would exchange Ambassadors with each other, while smaller monarchies and republics only sent Ministers. Because of diplomatic reciprocity, Great Powers would only send a Minister to a smaller monarchy or a republic. For example, in the waning years of the Second French Empire, the United Kingdom sent an Ambassador to Paris, while Sweden-Norway and the United States sent Ministers.

...
Wikipedia