Entries starting with H
- Haiti: Geography, History, Government and Key FactsHaiti is a Caribbean nation on Hispaniola's western third, founded by a slave revolt in 1804 and now facing severe political and economic crisis.
- Half-lifeA half-life is the time it takes for half the atoms in a radioactive sample to decay into something else.
- Hanoi: Geography, History, Culture and Key FactsHanoi is Vietnam's capital, a nearly thousand-year-old city on the Red River built around Hoan Kiem Lake and its Turtle Tower.
- Havana: Cuba’s Historic CapitalHavana is the capital of Cuba, founded by the Spanish in 1519, with an old town recognized as a UNESCO World Heritage Site.
- Helsinki: Finland’s Design CapitalHelsinki is Finland's capital and largest city, a Baltic Sea port founded in 1550 and known for design, sauna culture, and island fortresses.
- Herd immunityHerd immunity is the indirect protection people get from an infectious disease once enough of the population around them is immune.
- Ho Chi Minh City: Geography, History, Culture and Key FactsHo Chi Minh City, formerly Saigon, is Vietnam's largest city and commercial center, capital of South Vietnam until 1975.
- Honduras: Geography, History, Government and EconomyHonduras is a Central American country between Guatemala, El Salvador, and Nicaragua, known for the Maya ruins of Copan and its Caribbean coast.
- Hong Kong: Special Administrative RegionA Special Administrative Region of China on the Pearl River Delta, known worldwide for Victoria Harbour's skyline and its standing as a top global financial center.
- Houston: History, Geography, Culture and Key FactsHouston is the fourth-largest U.S. city, a Texas Gulf Coast hub for energy, shipping, and NASA human spaceflight.
- Hungary: Geography, History and Key FactsHungary is a landlocked Central European country on the Danube known for its 1000 CE founding, EU and NATO membership, and Budapest landmarks.
- Hyderabad: Geography, History, Culture and Key FactsHyderabad is the capital of Telangana, India, founded around Charminar in 1591 and now a major technology hub.
- HydropowerHydropower is electricity made from moving water, usually by letting it fall through a turbine, and it is the largest renewable electricity source.
- HypertensionHypertension is blood pressure that stays too high over time, straining the heart, blood vessels, brain and kidneys.
- HypotensionHypotension is the medical term for low blood pressure, generally a reading below 90/60 mmHg, which may or may not cause symptoms.