Bosnia and Herzegovina (Bosna i Hercegovina / , pronounced [bsna i xrtseoina]), abbreviated BiH or B&H, sometimes called BosniaHerzegovina and often known informally as Bosnia, is a country at the crossroads of south and southeast Europe, located in the Balkans. The capital and largest city is Sarajevo. Bosnia and Herzegovina borders Serbia to the east, Montenegro to the southeast, and Croatia to the north and southwest. It is not entirely landlocked; in the south it has a narrow coast on the Adriatic Sea within the Mediterranean, which is about 20 kilometres (12 miles) long and surrounds the town of Neum. Bosnia, which is the inland region of the country, has a moderate continental climate with hot summers and cold, snowy winters. In the central and eastern regions of the country, the geography is mountainous, in the northwest it is moderately hilly, and in the northeast it is predominantly flat. Herzegovina, which is the smaller, southern region of the country, has a Mediterranean climate and is mostly mountainous.

The area that is now Bosnia and Herzegovina has been inhabited by human beings since at least the Upper Paleolithic, but evidence suggests that during the Neolithic age, permanent human settlements were established, including those that belonged to the Butmir, Kakanj, and Vuedol cultures. After the arrival of the first Indo-Europeans, the area was populated by several Illyrian and Celtic civilizations. Culturally, politically, and socially, the country has a rich and complex history. The ancestors of the South Slavic peoples that populate the area today arrived during the 6th through the 9th century. In the 12th century, the Banate of Bosnia was established; by the 14th century, this had evolved into the Kingdom of Bosnia. In the mid-15th century, it was annexed into the Ottoman Empire, under whose rule it remained until the late 19th century. The Ottomans brought Islam to the region, and altered much of the country's cultural and social outlook.

From the late 19th century until World War I, the country was annexed into the Austro-Hungarian monarchy. In the interwar period, Bosnia and Herzegovina was part of the Kingdom of Yugoslavia. After World War II, it was granted full republic status in the newly formed Socialist Federal Republic of Yugoslavia. In 1992, following the breakup of Yugoslavia, the republic proclaimed independence. This was followed by the Bosnian War, which lasted until late 1995 and was brought to a close with the signing of the Dayton Agreement.

Today, the country is home to three main ethnic groups, designated "constituent peoples" in the country's constitution. The Bosniaks are the largest group of the three, the Serbs are the second-largest, and the Croats are the third-largest. In English, all natives of Bosnia and Herzegovina, regardless of ethnicity, are called Bosnian. Minorities, who under the constitution are categorized as "others", include Jews, Roma, Albanians, Montenegrins, Ukrainians and Turks.

Bosnia and Herzegovina has a bicameral legislature and a three-member presidency made up of one member from each of the three major ethnic groups. However, the central government's power is highly limited, as the country is largely decentralized. It comprises two autonomous entitiesthe Federation of Bosnia and Herzegovina and Republika Srpskaand a third unit, the Brko District, which is governed by its own local government. The Federation of Bosnia and Herzegovina furthermore consists of 10 cantons.

Bosnia and Herzegovina is a developing country and ranks 73rd in human development. Its economy is dominated by industry and agriculture, followed by tourism and the service sector. Tourism has increased significantly in recent years. The country has a social-security and universal-healthcare system, and primary- and secondary-level education is tuition-free. It is a member of the UN, the Organization for Security and Co-operation in Europe, the Council of Europe, the Partnership for Peace, and the Central European Free Trade Agreement; it is also a founding member of the Union for the Mediterranean, established in July 2008. The country is an applicant for membership in the European Union and has been a candidate for NATO membership since April 2010, when it received a Membership Action Plan.

Serbia ( (listen), SUR-bee-ə; Serbian: Србија, Srbija, pronounced [sř̩bija] (listen)), officially the Republic of Serbia (Serbian: Република Србија, Republika Srbija, pronounced [repǔblika sř̩bija] (listen)), is a landlocked country in Southeast Europe, at the crossroads of the Pannonian Plain and the Balkans. It shares land borders with Hungary to the north, Romania to the northeast, Bulgaria to the southeast, North Macedonia to the south, Croatia and Bosnia and Herzegovina to the west, and Montenegro to the southwest, and claiming a border with Albania through the disputed territory of Kosovo. Serbia has a population of roughly 7 million inhabitants. Its capital Belgrade is also the largest city.

Continuously inhabited since the Paleolithic Age, the territory of modern-day Serbia faced Slavic migrations in the 6th century, establishing several regional states in the early Middle Ages at times recognised as tributaries to the Byzantine, Frankish and Hungarian kingdoms. The Serbian Kingdom obtained recognition by the Holy See and Constantinople in 1217, reaching its territorial apex in 1346 as Serbian Empire. By the mid-16th century, the Ottomans annexed the entirety of modern-day Serbia; their rule was at times interrupted by the Habsburg Empire, which began expanding towards Central Serbia from the end of the 17th century while maintaining a foothold in Vojvodina. In the early 19th century, the Serbian Revolution established the nation-state as the region's first constitutional monarchy, which subsequently expanded its territory. Following casualties in World War I, and the subsequent unification of the former Habsburg crownland of Vojvodina with Serbia, the country co-founded Yugoslavia with other South Slavic nations, which would exist in various political formations until the Yugoslav Wars of the 1990s. During the breakup of Yugoslavia, Serbia formed a union with Montenegro, which was peacefully dissolved in 2006, restoring Serbia's independence as a sovereign state for the first time since 1918. In 2008, representatives of the Assembly of Kosovo unilaterally declared independence, with mixed responses from the international community while Serbia continues to claim it as part of its own sovereign territory.

Serbia is an upper-middle income economy, ranked 64th in the Human Development Index domain. It is a unitary parliamentary constitutional republic, member of the UN, CoE, OSCE, PfP, BSEC, CEFTA, and is acceding to the WTO. Since 2014, the country has been negotiating its EU accession, with the aim of joining the European Union by 2025. Serbia formally adheres to the policy of military neutrality. The country provides universal health care and free primary and secondary education to its citizens.