Beginning in the 21st century, the world population reached approximately 6 billion and has since grown to over 7 billion. Population density is measured as the number of people per square kilometer, and can be categorized as high (over 200 people/sq km), middle (11-50 people/sq km) or low (1 person/sq km). Population growth or change refers to the change in a population's size over a specific time period, and can be positive if the birth rate exceeds the death rate, or negative if the birth rate falls below the death rate. In addition to births and deaths, migration between locations also impacts population size.

2. Beginning of 21st century the population
measured was approx 6 billion. Till now
population has crossed from 7 billion.
Population density :
Population / Area
Density of an area is categorised as:
1.High density(more than 200 prsns per sq.km)
2. Middle density(11 to 50 prsns persq.km)
3.Low density(1 prsns per sq.km)

3. Factors affecting population distribution:

6. Population growth or change
Population change refers to change in the number
of people during a specific time period.
जनसंख्या परिवर्तन से र्ात्पयत एक ववशिष्ट
समयावधि के दौिान लोगों की संख्या में परिवर्तन
से है|
Population growth is the rate at which
a population grows or expands. It can positive as
well as negative also.
जनसंख्या वृद्धि वह दि है जजस पि जनसंख्या
बढ़र्ी या फै लर्ी है। यह सकािात्मक होने के
साथ-साथ नकािात्मक भी हो सकर्ा है।

7. When birth rate is more
than the death rate is
called positive growth.
On the other hand, when
birth rate decreases below
the death rate is called
negative growth.
जब जन्म दि मृत्यु दि से
अधिक होर्ी है र्ो इसे
सकािात्मक वृद्धि कहा
जार्ा है।
दूसिी ओि, जब जन्म दि
मृत्यु दि से कम हो जार्ी
है, र्ो इसे नकािात्मक
वृद्धि कहा जार्ा है।

10. The crude birth rate (CBR) is expressed as number
of live births in a year per thousand of women. It
is calculated as:
CBR=Bi/P*1000
CBR = Crude Birth Rate; Bi = live births during the
year; P=Mid year population of the area.
Crude Death Rate (CDR) is a simple method of
measuring mortality of any area. CDR is
expressed in terms of number of deaths in a
particular year per thousand of population in a
particular region. CDR is calculated as:
CDR= D/P*1000
Here, CDR=Crude Death Rate; D= Number of
deaths; P=Estimated mid-year population of that
year

11. Migration Apart from birth and death there is
another way by which the population size
changes. When people move from one place to
another, the place they move from is called the
Place of Origin and the place they move to is
called the Place of Destination.
Immigration: Migrants who move into a new place
are called Immigrants.
Emigration: Migrants who move out of a place are
called Emigrants.

12. There are two sets of factors that influence
migration:

14. Some Basic Concepts of
Population Geography
Growth of Population : Change of population in
particular area between two points of time is
known as growth of population.
Growth Rate of Population : This is the change of
population expressed in percentage.
Natural Growth of Population: This is the
population increased by difference between
births and deaths In a particular region between
two points of time.
Natural Growth = Births – Deaths
Actual Growth of Population : This is Births –
Deaths + In Migration – Out Migration

15. Positive Growthof Population:
This happens when the birth rate is more than
the death rate between two points of time or
when people from other countries migrate
permanently to a region.
Negative Growthof Population:
If the population decreases between two points
of time it is known as negative growth of
population. It occurs when the birth rate falls
below the death rate or people migrate to
other countries.