Natural increase in population means excess of births over deaths. This means that the number of births in a population is greater than the number of deaths in a given period of time, usually a year.
Natural increase is an important factor in determining population growth. When there are more births than deaths, the population increases naturally without the need for migration. This can have significant implications for a country's economy and social structure, as a growing population can place pressure on resources and infrastructure.
It is important to note that natural increase is just one factor that affects population growth. Migration, both immigration and emigration, can also significantly impact population size. However, when natural increase is positive, it means that the population is growing through the natural process of births and deaths.