Glossary

Every indicator published on this site, with its definition, unit, and source. Concepts common to all of them are defined at the end.

Fertility

Abortion Rateper 1,000 women 15–49: Induced abortions per 1,000 women aged 15–49 per year. Compiled from WHO and Guttmacher Institute estimates; reporting completeness varies by country. Source: WHO / Guttmacher Institute.
Adolescent Fertility Rateper 1,000 women 15–19: Births per 1,000 women aged 15–19. Typically falls earlier and faster than overall fertility as schooling and contraception spread, which makes it a useful marker of how far a country is through the fertility transition. Source: World Bank Open Data.
City Total Fertility Ratebirths per woman: Total fertility rate for a city or matching administrative geography (prefecture, borough set, département, etc.), compiled from national statistical offices. Geography notes on each series clarify the exact unit. Source: National statistical offices (vital statistics & census).
Contraceptive Prevalence, Any Method% of women 15–49: Share of married or in-union women aged 15–49 using any method of contraception. Survey-based, so values exist only for the years a country ran a demographic or health survey and gaps of a decade are common. Source: World Bank Open Data.
Crude Birth Rateper 1,000 people: Live births per 1,000 people per year. Not adjusted for age structure, so a country with many young adults shows a higher rate than an older one even at identical fertility. Source: World Bank Open Data.
General Fertility Rateper 1,000 women 15–44: Live births per 1,000 women ages 15–44. Common U.S. NCHS state fertility measure (distinct from total fertility rate). Source: National statistical offices (vital statistics & census).
Provisional Total Fertility Ratebirths per woman: Provisional / nowcast total fertility rate compiled from national statistical offices (via BirthGauge). Covers recent years ahead of World Bank final series. Partial-year estimates may be revised. Source: BirthGauge provisional fertility tracker.
Total Fertility Ratebirths per woman: Average number of children that would be born to a woman over her lifetime given current age-specific fertility rates. Source: World Bank Open Data.

Population

Age Dependency Ratio% of working-age population: People under 15 and over 64 per 100 people of working age. A high ratio can mean many children or many pensioners — opposite fiscal situations — so read it alongside the age-structure shares. Source: World Bank Open Data.
City Population Age Share% of population: Share of the city population in broad age groups (0–14, 15–64, 65+), from national censuses and official estimates. Breakdown via dimension=age. Source: National statistical offices (vital statistics & census).
Female Share of Population% of population: Women as a share of the total population. Departures from roughly 50% reflect sex selection at birth, the gap between male and female mortality, and heavily sex-imbalanced labour migration. Source: World Bank Open Data.
Population Ages 0–14 (% of total)% of population: Share of the population aged 0–14. Used to anchor the current age structure for projections. Source: World Bank Open Data.
Population Ages 15–64 (% of total)% of population: Share of the population of working age (15–64). Used to anchor the current age structure for projections. Source: World Bank Open Data.
Population Ages 65+ (% of total)% of population: Share of the population aged 65 and over. Used to anchor the current age structure for projections. Source: World Bank Open Data.
Population Densitypeople per sq km: People per square kilometre of land area. Land area includes desert, mountain and ice, so national density says little about how crowded the inhabited parts of a country actually are. Source: World Bank Open Data.
Population Growth% annual: Annual percentage change in total population, combining births, deaths, and net migration. A country can grow while births fall, if migration more than compensates. Source: World Bank Open Data.
Rural Population (% of total)% of total: Share of people living outside areas classified as urban — the complement of the urban share. Each country sets its own urban definition, so this reads best within a country over time rather than across borders. Source: World Bank Open Data.
Total Populationpeople: Total resident population, all ages and both sexes. Source: World Bank Open Data.
Urban Agglomeration Populationpeople: Population of the urban agglomeration (contiguous built-up area), annual 1950–2035. Estimates through 2018 and UN projections thereafter. Source: UN World Urbanization Prospects 2018.
Urban Population% of total: Share of the population living in urban areas (%). Source: World Bank Open Data.
Urban Population Growth% annual: Annual change in the population living in urban areas. Combines natural increase in cities, migration from the countryside, and places being reclassified as urban — the third can move the series without anyone moving house. Source: World Bank Open Data.

Migration

City Foreign-born / Foreign Citizenship Share% of population: Share of the city population that is foreign-born or holds foreign citizenship, per the definition used by the national statistical office (noted per series). Source: National statistical offices (vital statistics & census).
Foreign-born Populationpeople: International migrant stock — the number of people living in a country who were born in another country (the immigrant / diaspora population). Source: World Bank Open Data.
Foreign-born Population (% of total)% of population: International migrant stock as a share of the total population — how large the foreign-born / diaspora population is relative to the country. Source: World Bank Open Data.
Foreign-born Unemployment Rate% of labour force: Unemployment rate of foreign-born persons aged 15–64, as a share of the foreign-born labour force. OECD labour-market outcomes of immigrants. Source: OECD Data.
Native-born Unemployment Rate% of labour force: Unemployment rate of native-born persons aged 15–64, as a share of the native-born labour force. OECD labour-market outcomes of immigrants. Source: OECD Data.
Net Migrationpeople: Net number of migrants (immigrants minus emigrants) in a year. Source: World Bank Open Data.

Mortality

Crude Death Rateper 1,000 people: Deaths per 1,000 people per year. Not adjusted for age structure, so an ageing country can show a rising rate while mortality risk at every age is still falling. Source: World Bank Open Data.
Historic Crude Death Rateper 1,000 people: Deaths per 1,000 people per year from the Human Mortality Database (via Our World in Data). Covers countries with long vital-registration series, in some cases back to the mid-18th century. Not age-standardized. Source: Human Mortality Database.
Infant Mortality Rateper 1,000 live births: Deaths before the first birthday per 1,000 live births. Sensitive to registration practice at the edge of viability: countries that record extremely premature births as live births rather than stillbirths report higher rates for the same underlying medical outcomes. Source: World Bank Open Data.
Life Expectancy at Birthyears: Number of years a newborn would live if mortality patterns at birth stayed constant. Pre-1960 values from Our World in Data long-run reconstructions (Riley, Zijdeman, HMD, UN); from 1960 World Bank WDI. Source: World Bank Open Data.
Life Expectancy at Birth, Femaleyears: Years a newborn girl would live under current mortality patterns. Women outlive men almost everywhere; the size of the gap, not its direction, is what varies. Source: World Bank Open Data.
Life Expectancy at Birth, Maleyears: Years a newborn boy would live under current mortality patterns. Read against the female series: the gap runs from about two years to over ten, widening where male deaths from injury, alcohol and smoking are common. Source: World Bank Open Data.
Maternal Mortality Ratioper 100,000 live births: Deaths from causes related to pregnancy or childbirth per 100,000 live births, within 42 days of the end of pregnancy. A modelled estimate — few countries measure this directly with complete civil registration. Source: World Bank Open Data.
Suicide Mortality Rateper 100,000: Suicide deaths per 100,000 people, age-standardised WHO estimate. Classification depends on legal and religious context as well as medicine, and undercounting is thought to be substantial in some countries. Source: World Bank Open Data.
Under-five Mortality Rateper 1,000 live births: Deaths of children under age 5 per 1,000 live births. Long-run series from Our World in Data (Gapminder historical estimates and UN IGME). Source: Our World in Data.

Economy

City Median Household Incomecurrent US$: Median household income for the city (Census place), U.S. dollars. U.S. cities from ACS. Source: U.S. Census Bureau (ACS / Decennial).
Exports of Goods and Services (% of GDP)% of GDP: Exported goods and services as a share of GDP — roughly, how exposed an economy is to world demand. Can exceed 100% in entrepôt economies where imports are processed and re-exported. Source: World Bank Open Data.
Female Labour Force Participation% of women 15+: Share of women aged 15 and over who are working or looking for work, modelled ILO estimate. Historically inversely related to fertility, though across rich countries the correlation has reversed since the 1980s — the highest-participation countries now tend to have the higher birth rates. Source: World Bank Open Data.
GDP (constant 2015 US$)constant 2015 US$: Total output valued at 2015 prices, so changes over time show real growth rather than inflation. Converted at 2015 exchange rates, which makes it the right series for tracking one country through time but a poorer one for comparing levels between countries. Source: World Bank Open Data.
GDP (current US$)current US$: Market value of all goods and services produced in a year, converted to US dollars at market exchange rates. Measured in current prices, so figures from different years are not directly comparable — part of any increase is inflation and currency movement rather than more output. Source: World Bank Open Data.
GDP Growth% annual: Annual change in GDP measured at constant prices. Unlike the level figures, this series is adjusted for inflation, so it reflects real changes in output. Source: World Bank Open Data.
GDP per Capita (constant 2015 US$)constant 2015 US$: Output per person at constant 2015 prices. Use this rather than the current-dollar series to ask whether a country actually produces more per person than it did a decade ago, since inflation is removed. Source: World Bank Open Data.
GDP per Capita (current US$)current US$: GDP divided by midyear population, at market exchange rates. Not adjusted for local price levels, so it understates real living standards in countries where goods and services are cheap. Source: World Bank Open Data.
GDP per Capita, PPP (constant 2021 international $)constant 2021 international $: Purchasing-power-parity output per person held at constant 2021 prices, adjusted for both local price levels and inflation. The most directly comparable living-standards series on this site, across countries and across years. Source: World Bank Open Data.
GDP per Capita, PPP (current international $)current international $: Output per person converted at purchasing-power-parity rates instead of market exchange rates, so a dollar buys a comparable basket of goods in every country. The standard measure for comparing material living standards across countries. Source: World Bank Open Data.
Gini Indexindex (0–100): Income inequality on a 0–100 scale, where 0 is perfect equality and 100 is one household holding all income. Built from household surveys run in different years and to different designs, so coverage is patchy and cross-country gaps of a point or two are not meaningful. Source: World Bank Open Data.
GNI per Capita, Atlas Method (current US$)current US$: Income earned by a country's residents per person, smoothed over three years by the World Bank Atlas method. GNI counts income wherever residents earn it, so it diverges from GDP where foreign-owned profits or remittances are large. This is the series used to assign income groups. Source: World Bank Open Data.
Inflation, Consumer Prices% annual: Annual change in the cost of a representative basket of consumer goods and services. Each country sets its own basket and method, so the direction and size of movements travel better across borders than the exact levels. Source: World Bank Open Data.
Unemployment Rate% of labour force: Share of the labour force without work but available for and seeking employment, harmonised to the ILO definition. People who have stopped looking are outside the labour force and are not counted, so the rate can fall as discouragement rises. Source: World Bank Open Data.

Society

Access to Electricity% of population: Share of the population with access to electricity, counting both grid connections and off-grid supply. Having a connection is not the same as having reliable power. Source: World Bank Open Data.
Births Outside Marriage% of births: Share of live births to unmarried mothers (%). Compiled from OECD and Eurostat. Source: OECD Data.
Crude Divorce Rateper 1,000 people: Divorces per 1,000 population per year. Compiled from OECD, Eurostat and UN statistics. Source: OECD Data.
Individuals Using the Internet% of population: Share of the population that used the internet in the previous three months. Some countries report from household surveys and others from operator data, which counts subscriptions rather than people. Source: World Bank Open Data.

Crime

Foreign Citizenship Share of Prisoners% of prisoners: Share of persons held in prison who hold foreign citizenship (%). Eurostat crim_pris_ctz. Citizenship is not the same as immigrant ancestry or migration background. Source: Eurostat.
Intentional Homicide Rateper 100,000: Intentional homicides per 100,000 people. Source: World Bank Open Data.

Housing

Home Ownership Rate% of households: Share of households that own their home (%). Compiled from OECD, Eurostat and national statistics. Source: OECD Data.

Health

Health Expenditure (% of GDP)% of GDP: All current spending on health, public and private, as a share of GDP. A ratio rather than a level: it can be high because care is expensive or because GDP is small. Source: World Bank Open Data.
Hospital Bedsper 1,000 people: Inpatient beds per 1,000 people across public, private and specialised facilities. Bed counts have fallen in most rich countries because stays are shorter and more surgery is same-day, not because capacity collapsed. Source: World Bank Open Data.

Education

Adult Literacy Rate% of adults: Share of people aged 15 and over able to read and write a short simple statement about their everyday life. Usually collected by self-report in censuses and surveys, which tends to overstate ability. Source: World Bank Open Data.
Government Expenditure on Education (% of GDP)% of GDP: Public spending on education at all levels as a share of GDP. Excludes private tuition and household spending, which is a large share of the total in parts of East Asia and Latin America. Source: World Bank Open Data.
School Enrollment, Secondary (% gross)% gross: Secondary enrolment as a share of the population of official secondary-school age. Gross ratios count over-age and under-age pupils, so a value above 100% means repetition or late entry, not universal attendance. Source: World Bank Open Data.
School Enrollment, Tertiary (% gross)% gross: Higher-education enrolment as a share of the population in the five years following secondary school. Rising tertiary enrolment among women is one of the strongest correlates of later and lower childbearing. Source: World Bank Open Data.

Statistical concepts

Estimate: A value for a past or current year produced by a statistical agency from registration data, censuses, or surveys. Estimates are revised as better information arrives.
Projection: A modelled value for a future year, conditional on assumptions about fertility, mortality, and migration. A projection is not a forecast or a prediction of what will happen.
Provisional figure (nowcast): An early value published before the final annual statistics, often covering part of a year. Provisional figures are the most current numbers available and the most likely to be revised.
Replacement-level fertility: The total fertility rate at which a generation exactly replaces itself, about 2.1 births per woman in countries with low child mortality. Sustained rates below this level shrink a population over the long run, absent migration.
Period vs cohort measure: A period measure such as the total fertility rate describes one calendar year as if current rates applied for a whole lifetime. A cohort measure follows real people over time. Period rates react faster to shifts in the timing of births.
Crude rate: An event count divided by total population, usually per 1,000 people. Crude rates are not adjusted for age structure, so an older population shows a higher crude death rate even with identical mortality risk at every age.
Age-standardised rate: A rate recalculated against a common reference age structure so that populations of different ages can be compared directly.
Foreign-born vs foreign citizenship: Foreign-born counts where a person was born. Foreign citizenship counts the passport they hold. The two differ substantially in countries where naturalisation is common, and neither is the same as ancestry or migration background.
Net migration: Arrivals minus departures over a period. A net figure of zero can mean no movement at all, or very large flows in both directions that happen to cancel out.
Aggregate: A region, income group, or world total rather than a single country. Aggregates are excluded from country rankings and maps on this site.

Details of how these series are collected and combined are on the methodology page. A full list of providers is on the sources page.