San Marino in the context of "Constitutional republic"

The European Union Customs Union (EUCU), formally known as the Community Customs Union, is a customs union which consists of all the member states of the European Union (EU), Monaco, and the British Overseas Territory of Akrotiri and Dhekelia. Some detached territories of EU states do not participate in the customs union, usually as a result of their geographic separation. In addition to the EUCU, the EU is in customs unions with Andorra, San Marino and Turkey (with the exceptions of certain goods), through separate bilateral agreements.

There are no tariffs or non-tariff barriers to trade between the members of the customs union and—unlike a free trade area—members of the customs union impose a common external tariff on all goods entering the union.

A microstate or ministate is a sovereign state having a very small population or land area, usually both. However, the meanings of "state" and "very small" are not well-defined in international law. Some recent attempts to define microstates have focused on identifying qualitative features that are linked to their size and population, such as partial delegation of their sovereignty to larger states, such as for international defense.

Commonly accepted examples of microstates include five historic European microstates: Andorra, Liechtenstein, Monaco, San Marino, and Vatican City. Malta and Luxembourg are sometimes included in that list but are generally considered too populous to be genuine microstates. Other examples are small, isolated island states in the Pacific Ocean: Nauru, Palau, Niue, Cook Islands and Tuvalu. Some small Caribbean countries such as Saint Kitts and Nevis, Barbados, Antigua and Barbuda, Grenada, Saint Vincent and the Grenadines may be considered microstates by some but are often not included due to them being grouped together as small island countries. Singapore and Bahrain are sometimes considered microstates but some argue are too populous, self reliant or powerful to be considered true microstates and their island status can play an important factor too.The smallest political entity recognized as a sovereign state is Vatican City, with fewer than 1,000 residents and an area of only 49 hectares (120 acres). Some microstates – such as Singapore, Monaco and Vatican City – are city-states consisting of a single municipality.

The Italian Peninsula (Italian: penisola italica or penisola italiana) is located within the Italian geographical region; it extends from the southern Alps in the north to the central Mediterranean Sea in the south which comprises much of the country of Italy and the enclaved microstates of San Marino and Vatican City.The peninsula is also known as the Italic Peninsula, Apennine Peninsula, Italian Boot, or Mainland Italy.

Italy, officially the Italian Republic, is a country in Southern and Western Europe. It consists of a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land border, as well as nearly 800 islands, notably Sicily and Sardinia. Italy shares land borders with France to the west; Switzerland and Austria to the north; Slovenia to the east; and the two enclaves of Vatican City and San Marino. It is the tenth-largest country in Europe by area, covering 301,340 km (116,350 sq mi), and the third-most populous member state of the European Union, with nearly 59 million inhabitants. Italy's capital and largest city is Rome; other major cities include Milan, Naples, Turin, Palermo, Bologna, Florence, Genoa, and Venice.

The history of Italy goes back to numerous Italic peoples – notably including the ancient Romans, who conquered the Mediterranean world during the Roman Republic and ruled it for centuries during the Roman Empire. With the spread of Christianity, Rome became the seat of the Catholic Church and the Papacy. Barbarian invasions and other factors led to the decline and fall of the Western Roman Empire between late antiquity and the Early Middle Ages. By the 11th century, Italian city-states and maritime republics expanded, bringing renewed prosperity through commerce and laying the groundwork for modern capitalism. The Italian Renaissance flourished during the 15th and 16th centuries and spread to the rest of Europe. Italian explorers discovered new routes to the Far East and the New World, contributing significantly to the Age of Discovery.

Southern Europe is also known as Mediterranean Europe, as its geography is marked by the Mediterranean Sea. Definitions of southern Europe include some or all of these countries and regions: Albania, Andorra, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Gibraltar, Greece, Italy, Kosovo, Malta, Monaco, Montenegro, North Macedonia, Portugal, San Marino, Serbia, Slovenia, southern France, southern Romania, Spain, Ticino (Switzerland), Turkey, and Vatican City.

Southern Europe is focused on the three peninsulas located in the extreme south of the European continent. These are the Iberian Peninsula, the Italian Peninsula, and the Balkan Peninsula. These three peninsulas are separated from the rest of Europe by towering mountain ranges, respectively by the Pyrenees, the Alps and the Balkan Mountains. The location of these peninsulas in the heart of the Mediterranean Sea, as well as their mountainous reliefs, provide them with very different types of climates (mainly subtropical Mediterranean) from the rest of the continent. So, the Sirocco hot wind that originates in the heart of the Sahara blows over Italy, going up to the interior of the Alpine arc (Po Valley). The Alps prevent the Sirocco from spreading to the rest of Europe. And, conversely, the Alps and the Pyrenees protect the Italian and Iberian Peninsulas from the rains and icy winds from the south of France such as the Mistral and the Tramontane. When the Mistral and the Tramontane are blowing, this provokes an "upwelling" phenomenon on the French coast. They push the surface waters out to sea and bring deeper, cooler waters up to the seaside. Consequently, the temperature of the waters of the French coasts are therefore very cool even in summer, and not representative of the rest of the Mediterranean.This same kind of phenomenon takes place between the two slopes of the Balkan mountain range. These mountains have, moreover, been a serious handicap to population displacement, focusing southern Europe mainly on the Mediterranean world. The climate and cultures are therefore very specific.

An enclave is a territory that is entirely surrounded by the territory of only one other state or entity. An enclave can be an independent territory or part of a larger one. Enclaves may also exist within territorial waters. Enclave is sometimes used improperly to denote a territory that is only partly surrounded by another state. Enclaves that are not part of a larger territory are not exclaves, for example Lesotho (enclaved by South Africa), San Marino and Vatican City (both enclaved by Italy) are enclaved sovereign states.

An exclave is a portion of a state or district geographically separated from the main part, by some surrounding alien territory. Many exclaves are also enclaves, but an exclave surrounded by the territory of more than one state is not an enclave. The Azerbaijani exclave of Nakhchivan is an example of an exclave that is not an enclave, as it borders Armenia, Iran, and Turkey.