Bangladesh,cofficially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world and is among the most densely populated countries with a population of nearly 170 million in an area of 1,47,570 square kilometers (56,977 Sq. miles). Bangladesh shares land borders with India to the north, west, and east, and Myanmar to the southeast. To the south, it has a coastline along the Bay of Bengal. It is narrowly separated from Bhutan and Nepal by the Siliguri Corridor, and from China by the mountainous Indian state of Sikkim in the north. Dhaka, the capital and largest city, is the nation's political, financial, and cultural centre. Chittagong is the second-largest city and is the busiest port on the Bay of Bengal. The official language of Bangladesh is Bengali while Bangladeshi English is also used in the government and official documents alongside Bengali.

Bangladesh forms the sovereign part of the historic and ethnolinguistic region of Bengal, which was divided during the Partition of India in 1947 as part of a Muslim union with Pakistan, which it separated from in a bloody independence war in 1971. The country has a Bengali Muslim majority. Ancient Bengal was known as Gangaridai and was a bastion of pre-Islamic kingdoms. Muslim conquests after 1204 heralded the sultanate and Mughal periods, during which an independent Bengal Sultanate and a wealthy Mughal Bengal transformed the region into an important centre of regional affairs, trade, and diplomacy. After the Battle of Plassey in 1757, the maximum extent of British Bengal stretched from the Khyber Pass in the west to Singapore in the east. The creation of Eastern Bengal and Assam in 1905 set a precedent for the emergence of Bangladesh. The All India Muslim League was founded in Dhaka in 1906. In 1940, the first Prime Minister of Bengal, A. K. Fazlul Huq, supported the Lahore Resolution. Before the partition of Bengal, a Bengali sovereign state was first proposed by premier H. S. Suhrawardy. A referendum and the announcement of the Radcliffe Line established the present-day territorial boundary.

In 1947, East Bengal became the most populous province in the Dominion of Pakistan. It was renamed East Pakistan, and Dhaka became the country's legislative capital. The Bengali Language Movement in 1952; the East Bengali legislative election, 1954; the 1958 Pakistani coup d'état; the six point movement of 1966; and the 1970 Pakistani general election resulted in the rise of Bengali nationalism and pro-democracy movements. The refusal of the Pakistani military junta to transfer power to the Awami League, led by Sheikh Mujibur Rahman, led to the Bangladesh Liberation War in 1971. The Mukti Bahini, aided by India, waged a successful armed revolution. The conflict saw the Bangladeshi genocide and the massacre of pro-independence Bengali civilians, primarily targeting intellectuals and Hinduism. The new state of Bangladesh became the first constitutionally secular state in South Asia in 1972, with a large Hindu minority. Islam was declared the state religion in 1988. In 2010, the Bangladesh Supreme Court reaffirmed secular principles in the constitution.

A middle power in the Indo-Pacific, Bangladesh is home to the sixth-most spoken language in the world, the third-largest Muslim-majority population in the world, and the second-largest economy in South Asia. It maintains the third-largest military in the region and is the largest contributor of personnel to UN peacekeeping operations. Bangladesh is a unitary parliamentary republic based on the Westminster system. Bengalis make up almost 99% of the total population. The country consists of eight divisions, 64 districts and 495 subdistricts, as well as the world's largest mangrove forest. It hosts one of the largest refugee populations in the world due to the Rohingya genocide. Bangladesh faces many challenges, particularly corruption, political instability, overpopulation and effects of climate change. Bangladesh has been a leader within the Climate Vulnerable Forum. It hosts the headquarters of Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation (BIMSTEC). It is a founding member of the South Asian Association for Regional Cooperation (SAARC), as well as a member of the Organization of Islamic Cooperation and the Commonwealth of Nations.