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Access to safe water. Measured by the number of people who have a reasonable means of getting and adequate amount of clean water, expressed as a percentage of the total population. It reflects the health of a country's people and the country's ability to collect, clean, and distribute water. In urban areas "reasonable" access means there is a public fountain or water spigot located within 200 meters of the household. In rural areas, it implies that members of the household do not have to spend excessive time each day fetching water. Water is safe or unsafe depending on the amount of bacteria in it. An adequate amount of water is enough to satisfy metabolic, hygienic, and domestic requirements, usually about 20 liters (about 4 gallons) per person per day.

Access to sanitation. Refers to the share of the population with at least adequate excreta disposal facilities that can effectively prevent human, animal, and insect contact with excreta. Suitable facilities range from simple but protected pit latrines to flush toilets with sewerage. To be effective, all facilities must be correctly constructed and maintained.

Adult illiteracy rate. The proportion of the population over age fifteen who cannot, with understanding, read and write a simple statement about their everyday life and do simple mathematical calculations.

AIDS (Acquired ImmunoDeficiency Syndrome). The late stage of infection caused by a virus, the Human Immunodeficiency Virus (HIV). See HIV below.


Bilharzia. A life-threatening parasitic disease caused by a worm that lives in a host snail. Humans can become infected when they come in contact with water in ponds and rivers where the snail lives. Occurs most often in tropical regions. Also called schistosomiasis.

Billion. One billion equals 1,000,000,000 or one thousand million.

Biodiversity. The variability among living organisms from all sources, including land based and aquatic ecosystems, and the ecosystems of which they are part. These include diversity within species, between species, and of ecosystems. Diversity is the key to ensuring the continuance of life on Earth. It is also a fundamental requirement for adaptation and survival and continued evolution of species.

Birth rate. The number of births in a year per 1,000 population.


Capital. The money or wealth needed to produce goods and services. See also human capital and physical capital.

Carrying capacity. The population that an area will support without undergoing environmental deterioration.

Child mortality rate. The probablity of dying between the ages of one and five, if subject to current age-specific mortality rates.

Cholera. Any of several diseases of man and domestic animals usually marked by severe gastrointestinal symptoms.

Chronic disease. An illness, such as heart disease or asthma, that is ongoing or recurring but is not caused by infection and is not passed on by contact.

Commodity. See primary goods or products.


Death rate. The number of deaths in a year per 1,000 population.

Deforestation. The process of clearing of forests. Since trees root systems are essential for keeping top soil in place, deforestation can bring about soil erosion. In addition, loss of trees is said to contribute to global warming because trees reduce greenhouse gases and provide shade.

Demography. The statistical study of human populations, especially with reference to size and density, distribution and vital statistics.

Desertification. The process of becoming desert (as from land management or climate change).

Developing country. Low- and middle-income countries in which most people have a lower standard of living with access to fewer goods and services than do most people in high-income countries. There are currently about 125 developing countries with populations over 1 million; in 1998, their total population was more than 5.0 billion.

Diarrheal illness. A disease that affects the intestines. The victims of this disease, frequently children in low- and middle-income countries, may die from the resulting dehydration.

Diphtheria. An infectious disease caused by a bacteria which produces a poison that affects the tonsils, nose and/or skin. The symptoms include difficulty in breathing, high fever, and weakness. The poison also damages the heart and central nervous system, and can be fatal.


Economic growth/development. The process by which a country increases its ability to produce goods and services.

Economic depression. A period marked by low production and sales and a high rate of business failures and unemployment.

Ecosystem. A community of plants and animals existing in an environment that supplies them with water, air, and other elements they need for life.

Ecosystem integrity. The extent to which the interrelationships among and within ecosystems remain intact so that the number and variety of living organisms can be maintained.

Elephantiasis. A disease, often found in tropical countries, in which parts of the human body become enlarged. It is caused by small roundworms that are injected into the body by mosquitoes.

Environment. The complex set of physical, geographic, biological, social, cultural and political conditions that surround an individual or organism and that ultimately determines its form and nature of its survival.

Export. To sell goods or services to a buyer outside your country.


Factors of production. Input used to produce goods and services, for example, capital or labor.

Family planning. A health service that helps couples decide whether to have children, and if so, when and how many.

Fertility rate (total). The average number of children a woman will have during her lifetime. The total fertility rate in developing countries is between three and four; in industrial countries it is less than two.


Goods and services. Thingsthat are produced by a country's economy. Examples of goods include food, clothing, machines, and new roads. Examples of services include those of doctors, teachers, merchants, tourist agents, construction workers, and government officials.

GNI (gross national income). See GNP (gross national product)

GNP (gross national product). The value (in U.S. dollars) of a country's final output of goods and services in a year. The value of GNP can be calculated by adding up the amount of money spent on a country's final output of goods and services, or by totaling the income of all citizens of a country including the income from factors of production used abroad. Since 2001, the World Bank refers to the GNP as the GNI, gross national income.

GNP per capita. The dollar value of a country's final output of goods and services in a year (its GNP), divided by its population. It reflects the average income of a country's citizens. Knowing a country's GNP per capita is a good first step toward understanding the country's economic strengths and needs.Since 2001, the World Bank refers to the GNP per capita as the GNI per capita, gross national income per capita.

GNP per capita growth rate. The change in GNP per capita over a period, expressed as a percentage of GNP per capita at the start of the period.

Growth rate. The change (increase, decrease, or no change) in an indicator over a period of time, expressed as a percentage of the indicator at the start of the period. Growth rates contain several sets of information. The first is whether there is any change at all; the second is what direction the change is going in (increasing or decreasing); and the third is how rapidly that change is occurring. For example, if a country’s GNP growth rate for a particular year is more or less than zero, there has been a change in the amount of goods and services produced in that year. If the GNP growth rate is positive, the country is producing more goods and services at the end of the year than at the beginning. If the GNP growth rate is negative, the country is producing fewer goods and services than at the beginning of the year. Note that a change in GNP growth rate from 2% one year to 1% the next year does not mean that the total production of goods and services has decreased. As long as the growth rate is positive, the GNP is growing. The only time the production of goods and services has actually decreased is when the GNP growth rate is negative.


High-income country. A country having an annual gross national product (GNP) per capita equivalent to $9,361 or greater in 1998. Most high-income countries have an industrial economy. There are currently about 29 high-income countries in the world with populations of one million people or more. Their combined population is about 0.9 billion, less than one-sixth of the world’s population. In 2003, the cutoff for high-income countries was adjusted to $9,206 or more.

HIV (Human Immunodeficiency Virus). A virus that steadily weakens the body's defense (immune) system until it can no longer fight off infections such as pneumonia, diarrhea, tumors and other illnesses. All of which can be part of AIDS (Acquired ImmunoDeficiency Syndrome). Unable to fight back, most people die within three years of the first signs of AIDS appearing. Most of all HIV infections have been transmitted through unprotected sexual intercourse with someone who is already infected with HIV. HIV can also be transmitted by infected blood or blood products (as in blood transfusions), by the sharing of contaminated needles, and from an infected woman to her baby before birth, during delivery, or through breast-feeding. HIV is not transmitted through normal, day-to-day contact. (Source: UNAIDS)

Hookworm. An intestinal parasite found in tropical and subtropical regions. It passes through the skin, especially bare feet, and is spread by unsanitary conditions.

Human capital. People and their ability to be economically productive. Education, training, and health care can help increase human capital. See also capital and physical capital.

Hygiene. Practices, such as frequent hand washing, that help ensure cleanliness and good health.


Import. To buy goods and services from another country.

Immunization. A medical procedure that increases a person's resistance to contagious diseases such as measles, smallpox, whooping cough, diphtheria, and tetanus.

Indicator. A numerical measure of quality of life in a country. Indicators are used to illustrate progress of a country in meeting a range of economic, social, and environmental goals. Since indicators represent data that have been collected by a variety of agencies using different collection methods, there may be inconsistencies among them.

Industrial country. A country in which historically the greatest part of output has been accounted for by industry. However, the term is widely used to signify high-income economies.

Industrial waste. Material—for example, certain chemicals or even very hot water—left over from a manufacturing process. It can be harmful sometimes and may pollute the water and the environment if not treated and/or disposed of properly.

Infectious diseases. An illness that can be passed from one person to another.

Infant mortality rate. The number of infants, out of every 1,000 babies born in a given year, who die before reaching age 1. The lower the rate, the fewer the infant deaths, and generally the greater the level of health care available in a country.

Informal economy. The exchange of goods and services not accurately recorded in government figures and accounting. The informal economy, which is generally untaxed, commonly includes goods and services including day care, tutoring, or black market exchanges.

Investment. Money spent now in order to make the economy grow and have more money—or goods and services—later.


Life expectancy at birth. The average number of years newborn babies can be expected to live based on current health conditions. This indicator reflects environmental conditions in a country, the health of its people, the quality of care they receive when they are sick, and their living conditions.

Literacy. The ability to read and write a simple statement about one's everyday life and do simple mathematical calculations.

Low-income country. A country having an annual gross national product (GNP) per capita equivalent to $760 or less in 1998. The standard of living is lower in these countries; there are few goods and services; and many people cannot meet their basic needs. In 2003, the cutoff for low-income countries was adjusted to $745 or less. At that time, there were about 61 low-income countries with a combined population of about 2.5 billion people.


Manufactured products. Goods--for example, shoes, trucks, paper, radios, electric motors, and canned fruit-that are produced from raw materials by hand or by machine.

Measles. A contagious viral disease mostly occurring in children. Symptoms include red spots on the skin and fever.

Middle-income country. A country having an annual gross national product (GNP) per capita equivalent to more than $760 but less than $9,360 in 1998. The standard of living is higher than in low-income countries, and people have access to more goods and services, but many people still cannot meet their basic needs. In 2003, the cutoff for middle-income countries was adjusted to more than $745, but less than $9,206. At that time, there were about 65 middle-income countries with populations of one million or more. Their combined population was approximately 2.7 billion.


Natural resource accounting. The process of adjusting national accounts such as GNP to reflect the environmental costs of economic production. Although methods are still being developed, natural resource accounting strives to determine the costs of depleting natural resources and damaging the environment.

Natural resources. Materials that occur in nature and are essential or useful to humans, such as water, air, land, forests, fish and wildlife, topsoil, and minerals.


Physical capital. Things, such as machinery, tools, equipment, furniture, parts, and buildings, that are needed to produce goods and services. See also capital and human capital.

Polio. A viral disease causing inflammation of the nerve cells of the brain stem and spinal cord. Those who survive this disease often experience damage to their nervous system which can result in paralysis.

Population growth rate (average annual). The increase in a country's population during one year, divided by the population at the start of that year. It reflects the number of births and deaths during the period and the number of people moving to and from a country. The average annual population growth rates for a period of years provide a better picture than do rates for a single year. In 1998 total world population was more that 5.8 billion, and the average world population growth rate was between 1980 and 1998 1.6.

Population momentum. The tendency for population growth to continue beyond the time that replacement-level fertility has been achieved because of a relatively high concentration of people in the childbearing years. For example, the absolute numbers of people in developing countries will continue to increase over the next several decades even as the rates of population growth will decline. This phenomenon is due to past high fertility rates which results in a large number of young people. As these youth grow older and move through reproductive ages, the greater number of births will exceed the number of deaths in the older populations.

Population projections. Demographers make predictions about future population based on trends in fertility, mortality, and migration.

Prevalence of malnutrition under age 5. The percentage of children under five years of age whose health and growth are jeopardized by lack of proper food.

Primary goods or products. Goods--for example, iron ore, diamonds, wheat, copper, oil, or coffee-that are used or sold as they are found in nature. They are also called commodities.

Primary health care. Health services, including family planning, clean water supply, sanitation, immunization, and nutrition education, that are designed to be affordable for both the poor people who receive the services and the governments that provide them; the emphasis is on preventing disease as well as curing it.

Purchasing power parity (PPP). A method of measuring the relative purchasing power of different countries’ currencies over the same types of goods and services. Because goods and services may cost more in one country than in another, PPP allows us to make more accurate comparisons of standards of living across countries. PPP estimates use price comparisons of comparable items but since not all items can be matched exactly across countries and time, the estimates are not always “robust.”


Renewable. Able to be replaced or replenished, either by the earth's natural processes or by human action. Air, water, and forests are often considered to be example of renewable resources. However, due to local geographic conditions and costs involved, strong arguments can be made that water may not be a completely renewable resource in some parts of the world, especially in developing countries or in areas with limited groundwater supplies. Minerals and fossil fuels are examples of non-renewable resources.

Replacement level. The fertility level at which couples have the number of children required to replace themselves, this is about two children. When the replacement level is reached, population growth will stabilize in time. (See definitions for Population Momentum and Transition.)

Resources. The machines, workers, money, land, raw materials, and other things that a country can use to produce goods and services and to make its economy grow. Resources may be renewable or nonrenewable. Countries must use their resources wisely to ensure long term prosperity.


Safe water. Water that is safe for drinking and bathing including treated surface water and untreated but uncontaminated water, such as from springs, sanitary wells, and protected boreholes.

Sanitation. Maintaining clean, hygienic conditions that help prevent disease through services such as garbage collection and wastewater disposal.

Sanitation facilities. Basic sewerage and drainage systems that collect waste water and then clean and redistribute it.

Sewage. Refuse liquids or waste matter carried off by sewers.

Sewerage. A system of sewers or drainage pipes.

Silting. The process whereby waterways become choked by mud and soil that has washed off the land through erosion.

Social services. Services generally provided by the government that help improve people's standard of living; examples are public hospitals and clinics, good roads, clean water supply, garbage collection, electricity, and telecommunications.

Sources of water. House connection/yard tap: Piped water from the public water distribution system that reaches the home or yard. When people have house connections, they usually have indoor plumbing as well; if they have yard taps, they have to go outside to get water. Shallow well: A well dug on public or private property for public consumption. Public wells usually provide water for little or no cost; water from private wells is usually more expensive. Shallow wells are not always reliable sources of water because they can become contaminated by run off in the rainy season or dry up in the dry season. Yard well: A shallow well in a yard usually intended for private use. Standpost: An outside tap to which a number of households can go to get water. Public standposts are connected to the public water distribution system and controlled by the water company. Private standposts are not connected to the public water distribution system nor controlled by the water company. Private borehole and electric pump: A very deep well drilled into the ground using specialized machinery. Boreholes are used when the water is far below the surface or when the ground is too hard to dig a well by conventional means. Because they are so deep, they require an electric pump to bring water to the surface.

Sustainable development. Development that meets the needs of the people today without compromising the ability of future generations to meet their own needs.


Tetanus. A disease causing spasmodic contraction of voluntary muscles, usually near the neck and jaw. The infection that causes it usually enters through a deep wound.

Transition. Refers to the demographic change that is occurring in developing countries as they move to lower rates of fertility and mortality. Many factors contribute to transition including: improved health services, greater access to education and improved social and economic conditions. Several developing countries in Asia are now in the later stages of transition, while many countries in Sub-Saharan Africa are in the early stages of transition. Demographic transition is complete when fertility has reached replacement level, which is the case in most industrial countries.

Tuberculosis. An infectious disease which causes tubercles to form on the inside of lungs and body tissue. Symptoms include heavy coughing, fever, weight loss, and chest pain.

Typhoid. An illness which infects people through contaminated food or drink. The symptoms include fever, severe headaches, nausea, and severe loss of appetite.


Under-5 mortality rate. The probability that a newborn baby will die before reaching age five, if current living conditions stay the same. Unlike child mortality rates, under-5 mortality includes infant (0-1 year) deaths.

Urbanization. The process by which a country's population changes from primarily rural to urban. It is caused by the migration of people from the countryside to the city in search of better jobs and living conditions.


Wastewater. Water that has been used and is no longer clean.

Wastewater treatment. The process of removing pollutants from water that has been used. There are different stages of treatment. Primary sewage treatment involves screening the water to remove the largest solids from wastewater and then letting the water sit in settling tanks so that the smaller solids and particles sink to the bottom. Secondary treatment involves another stage in which microbes added to the wastewater to eat the biological pollutants, or the wastewater is put through another filter. Then the treated water is disinfected and released back into nature. The more steps included in the treatment, the more expensive the process.

Watershed. The specific land area that drains water into a river system or other body of water.

Whooping cough. A highly contagious respiratory disease that most often affects children. The symptoms are spasms of coughing with a deep, noisy "whooping" sound as the child gasps for air.

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