The article discusses ways to measure the number and variety of species in different habitats. It introduces terms like α-diversity, β-diversity, and γ-diversity to describe species diversity within a community, across habitats, and in a geographical area. Since it's hard to count every species, scientists use sampling methods to estimate the total number. Various techniques and models are used to estimate species richness and abundance. The article also covers ways to compare diversity between different samples and study community structure. Overall, the goal is to help with conservation efforts by understanding and managing species diversity effectively.