Population change refers to the change in the number of people living in a particular area. It is a measure of how the population of an area has increased or decreased over a specific period of time. Population change is a key indicator of demographic trends and can have significant social, economic, and environmental implications.

There are several factors that contribute to population change, including birth rate, death rate, migration, and natural disasters. These factors can cause the population of an area to either increase or decrease.

The key points to understand about population change are as follows:

1. Definition of population change:
- Population change refers to the change in the number of people living in a particular area.
- It is measured by comparing the population at the beginning and end of a specific time period.

2. Factors influencing population change:
- Birth rate: The number of births per 1,000 individuals in a population.
- Death rate: The number of deaths per 1,000 individuals in a population.
- Migration: The movement of people from one area to another.
- Natural disasters: Events such as earthquakes, floods, or epidemics that can cause a significant loss of life.

3. Calculation of population change:
- Population change can be calculated using the formula: Population change = (Births + Immigration) - (Deaths + Emigration).
- If the result is positive, it indicates population growth, while a negative result indicates population decline.

4. Importance of population change:
- Population change is an important indicator of demographic trends and can help in understanding the dynamics of a population.
- It can have significant social, economic, and environmental implications.
- Understanding population change is crucial for policy-making, resource allocation, and planning for the future.

In conclusion, population change refers to the change in the number of people living in a particular area. It is influenced by factors such as birth rate, death rate, migration, and natural disasters. Population change is an important indicator of demographic trends and has significant implications for society, the economy, and the environment.