Vietnam, officially the Socialist Republic of Vietnam (SRV; Cộng hòa Xã hội chủ nghĩa Việt Nam (About this sound listen)), is the easternmost country on the Indochina Peninsula in Southeast Asia. With an estimated 90.0 million inhabitants as of 2013, it is the world's 13th-most-populous country, and the eighth-most-populous Asian country. The name Vietnam translates as "Southern Viet" (synonymous with the much older term Nam Viet); it was first officially adopted in 1802 by Emperor Gia Long, and was adopted again in 1945 with the founding of the Democratic Republic of Vietnam under Ho Chi Minh. The country is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea to the east. Its capital city has been Hanoi since the reunification of North and South Vietnam in 1976.
Vietnam is located on the eastern Indochina Peninsula between the latitudes 8° and 24°N, and the longitudes 102° and 110°E. It covers a total area of approximately 331,210 km2 (127,881 sq mi), making it almost the size of Germany. The combined length of the country's land boundaries is 4,639 km (2,883 mi), and its coastline is 3,444 km (2,140 mi) long. At its narrowest point in the central Quảng Bình Province, the country is as little as 50 kilometres (31 mi) across, though it widens to around 600 kilometres (370 mi) in the north. Vietnam's land is mostly hilly and densely forested, with level land covering no more than 20%. Mountains account for 40% of the country's land area, and tropical forests cover around 42%.
Because of differences in latitude and the marked variety in topographical relief, the climate tends to vary considerably from place to place. During the winter or dry season, extending roughly from November to April, the monsoon winds usually blow from the northeast along the Chinese coast and across the Gulf of Tonkin, picking up considerable moisture. Consequently, the winter season in most parts of the country is dry only by comparison with the rainy or summer season. The average annual temperature is generally higher in the plains than in the mountains, and higher in the south than in the north. Temperatures vary less in the southern plains around Ho Chi Minh City and the Mekong Delta, ranging between 21 and 28 °C (69.8 and 82.4 °F) over the course of the year. Seasonal variations in the mountains and plateaus and in the north are much more dramatic, with temperatures varying from 5 °C (41.0 °F) in December and January to 37 °C (98.6 °F) in July and August.
Much of Vietnam's modern transport network was originally developed under French rule to facilitate the transportation of raw materials, and was reconstructed and extensively modernized following the Vietnam War.