Explain the meaning of word population?

It is defined as the permanent aggregation of individuals of the same kind which occur in a particular area at a particular time. Their ranking is lower than the species. The species has many populations. The population is described by time, space, number and kind. The population is not static. It keeps on changing with the passing time. So, time is the most important and crucial parameter which describes the population. The total number of individuals and their types play a crucial role in describing the population. The total number of individuals in the population makes a population size. It includes both the male and female sexes. The space denotes the area of the region where population resides. It is mentioned as the double dimensions for the land organisms. It is described as a three dimensional in the aquatic organisms.
The population density is also known as the number of individuals of species which are present in the per unit area and at that particular time. In this all the individuals are counted and are denoted by letter N which are present at that particular time and are divided by the number of units of space which is denoted by letter S. The total count and sampling are the main methods of counting. The total count includes all the individuals and the sampling includes the individuals in a particular area. The population density is equal to the number of individuals divided by the units of space.