The diplomatic corps is the collective body of foreign diplomats accredited to a particular country or body.
Diplomatic corps plaque used on some embassies and diplomatic missions
A letter of credence is a formal diplomatic letter that designates a diplomat as ambassador to another sovereign state. Commonly known as diplomatic credentials, the letter is addressed from one head of state to another, asking them to give credence to the ambassador's claim of speaking for their country. The letter is presented personally by the ambassador-designate to the receiving head of state in a formal ceremony, marking the beginning of the ambassadorship.
Letter of credence for the Czechoslovak Ambassador to Lithuania (1992), written in the traditional French and signed by President Václav Havel
British diplomat Sir Charles Stuart presenting his credentials to Emperor Pedro I of Brazil, who is flanked by his wife Maria Leopoldina, their daughter Maria da Glória (later Queen Maria II of Portugal), and other dignitaries (allegory), c. 1825
Ambassador Eugène-Richard Gasana of Rwanda presents his credentials to Russian President Vladimir Putin, attended by Russian Foreign Minister Sergey Lavrov (2007).
The Ambassador of Yugoslavia, Zdravko Pečar, presenting his letter of credence to the Head of state of Ghana, Ignatius Kutu Acheampong, in 1974.