A diplomatic mission is a group of people from one state or an international inter-governmental organization (such as the United Nations) present in another state to represent the sending state/organization in the receiving state. In practice, a diplomatic mission usually denotes the permanent mission, namely the office of a country's diplomatic representatives in the capital city of another country.
All missions to the United Nations are known simply as Permanent Missions, while missions to the European Union are known as "Permanent Representations" and the head of such a mission is typically both a Permanent Representative and an ambassador. European Union missions abroad as known as "delegations". Some countries have more particular naming for their missions and staff: a Vatican mission is headed by a Nuncio and consequently known as an Apostolic Nunciature, while Libya's missions were for a long time known as People's Bureaus and the head of the mission was a Secretary.
In the past a diplomatic mission headed by a lower ranking official (an envoy or minister resident) was known as a legation. Since the ranks of envoy and minister resident are effectively obsolete, the designation of legation is no longer used today. (See diplomatic rank.)
In cases of dispute, it is common for a country to recall its head of mission as a sign of its displeasure. This is less drastic than cutting diplomatic relations completely, and the mission will still continue operating more or less normally, but it will now be headed by a chargé d'affaires who may have limited powers. Note that for the period of succession between two heads of missions, a chargé d'affaires ad interim may be appointed as caretaker; this does not imply any hostility to the host country.
A Consulate is similar to (but not the same as) a diplomatic office, but with focus on dealing with individual persons and businesses, as defined by the Vienna Convention on Consular Relations. A Consulate or Consulate-General is generally a representative of the Embassy in locales outside of the capital city. For instance, The British Embassy to the United States is in Washington, D.C., and there are British Consulates in Los Angeles, New York City, Houston, and so on. The person in charge of a consulate or consulate-general is known as a consul or consul-general, respectively.
The term "embassy" is often used to refer to the building or compound housing an ambassador's offices and staff. Technically, "embassy" refers to the diplomatic delegation itself, while the office building in which they work is known as a chancery, but this distinction is rarely used in practice. Ambassadors reside in ambassadorial residences, which enjoy the same rights as missions.
Under international law, diplomatic missions enjoy an extraterritorial status and thus, although remaining part of the host country's territory, they are exempt from local law and in almost all respects treated as being part of the territory of the home country. They are also only required to pay taxes equal to their respective countries' guidelines.
As the host country may not enter the representing country's embassy without permission, embassies are sometimes used by refugees escaping from either the host country or a third country. For example, North Korean nationals, who would be arrested and deported from China upon discovery, have sought sanctuary at various third-country embassies in China. Once inside the embassy, diplomatic channels can be used to solve the issue and send the refugees to another country. Notable violations of embassy extraterritoriality include the Iran hostage crisis (1979–1981), the Japanese embassy hostage crisis which took place in Lima, Peru during 1996, and the 2006 embassy burnings in Iran, Lebanon and Syria of Danish, Norwegian and Chilean embassies.
Between members of the Commonwealth of Nations there are no embassies, but High Commissions, as Commonwealth nations share a special diplomatic relationship. It is generally expected that an embassy of a Commonwealth country in a non-Commonwealth country will do its best to provide diplomatic services to citizens from other Commonwealth countries if the citizen's country does not have an embassy in that country. Canadian and Australian nationals enjoy even greater cooperation between their respective consular services, as outlined in Canada/Australian Consular Services Sharing Agreement. The same kind of procedure is also followed multilaterally by the member states of the European Union (EU). European citizens in need of consular help in a country without diplomatic or consular representation of their own country may turn to any consular or diplomatic mission of another EU member state.
Nations that are not recognized have legations overseas but these are not recognized as having official diplomatic status as defined by the Vienna Convention. These de facto embassies are usually referred to as Representative Offices. Some examples of these types of missions: the Representative Office of the Turkish Republic of Northern Cyprus in Washington, D.C.; Somaliland's representatives in London, Addis Ababa, Rome, and Washington, D.C.; the Republic of Nagorno-Karabakh has a representative office in Washington, D.C.; the Taipei Economic and Cultural Office in Washington, D.C. (representing the Republic of China); and the American Institute in Taiwan (representing the United States in Taiwan). Under United States law, such offices are regarded by the State Department officially as "information centers" and the persons working in them do not have diplomatic visas, nor are credentials from their chiefs of mission accepted.
Countries that are not sovereign states may set up offices abroad, as in the case of Hong Kong, which government has set up Hong Kong Economic and Trade Offices in various locations. Such offices assume some of the non-diplomatic functions of diplomatic posts, such as promoting trade interests and providing assistance to its citizens and residents. They are nevertheless not diplomatic missions, their personnel are not diplomats and do not have diplomatic visas, although there may be legislation providing for personal immunities and tax privileges, as in the case of the HKETOs in London and Toronto, for example.
Some cities may host more than one mission from the same country. An example is Rome, where many states maintain missions to Italy, another to the Holy See and even another to the Sovereign Military Order of Malta. It is not customary for these missions to share premises nor diplomatic personnel. Presently only the Iraqi missions to Italy and the Holy See share premises; however, two ambassadors are appointed, one to each country. Geneva, a Swiss city hosting many international organizations, also has many missions.