A population refers to a group of individuals of the same species living in a defined geographical area and capable of interbreeding. Its study includes several important characteristics. Three of the most important are:
\begin{enumerate}
\item Population Density:
It refers to the number of individuals of a species per unit area or volume. Population density indicates how crowded or sparse a population is. For example, the population density of tigers in India is calculated as the number of tigers per 100 sq. km.
\item Natality (Birth Rate):
Natality is the rate at which new individuals are born in a population during a given period of time. It is a key factor contributing to population growth. High birth rate increases population size while low birth rate slows growth.
\item Mortality (Death Rate):
Mortality is the rate at which individuals die in a population during a given period of time. Mortality reduces population size and is influenced by environmental factors, diseases, and predation.
\end{enumerate}
Other Characteristics (for reference): Age distribution, sex ratio, dispersal, and growth patterns are also important in population studies.