Birth Rate  : number of birth that take place in  a population over a year . The birth rate (BR) is calculated by dividing the number of birth in an area over a year by the total population ; the result is the multiplied by 1000 .

Death Rate: number of death that take place in a population over a year . The death rate (DR) is calulated by dividing the number of deaths in an area over a year by the total population and multiplying the result by 1000.

Natural Increase: is the number of birth minus the number of death . (RNI) RATE NATURAL INCREASE  It can be calculate but dividing the natural increase by the total population and multiplying the result by 100.

Infant Mortality Rate: Is the number of deaths of infants under 1 year dividing by the number of birth in a year , per 100

Life Expectancy :  is the average years that one person may expert to live. It also shows welfare and economic and social status of a country .

Birth Control: methods of restricting the number of children born, usually through control or prevention of conception;
contraception.

Dependent Population:  those who rely on the working population for support e.g. the young and elderly.

Dependency Ratio :  the ratio between those of working age and those of non-working age. This is calculated as:  % pop aged 0-14 +% pop aged 65+% of population aged 15- 65 x 100

Family Planning :  using contraception to control the size of your family.

Population Piramids :   a graph which shows the age and sex structure of a place.

Replacement Rate :  percentage of a worker's pre-retirement income that is paid out by a pension program upon retirement

Fertility Rate:  

The average number of children born to a woman in her lifetime.*1000

Ageing Population: is a phenomenon that occurs when the median age of a country or region increases due to rising life expectancy and/or declining fertility rates. 

Population Distribution: is how people tend to live in uneven clusters on Earth's surface.

Population Density:  i s when you try to find out how many people live in an area, how you find the number of people that live in an area is you divide that number by square miles or square kilometers.

A More Economically Developed Country (MEDC) :  Countries with more resources, salaries and housing accessibility's are MEDC’s  , have a lower birth rate and also a low death rate due to advanced Medical Technology  and has low baby population and high elderly population  .

Less Economically Developed Country (LEDC):  have a high birth rate and 

also a high death rate due to poor health care and a different type of diseases The countries are also very poorly developed and the birth rate is high. Life is rather hard and people don’t have much money to get resources.

Overpopulation:  the condition of having a population so dense as to cause environmental deterioration, an impaired quality of life, or a population crash

Underpopulation: lacking the normal or required population density.