In biological studies, by default or design, the primary objective is to understand the relationships between the structure and the function of an organism or animal. Here, analysis of the avian (bird) lung is given to show the versatility and robustness of stereological techniques in analysing biological structures. Only basic understanding of mathematics, geometry and statistics is needed to do good stereology. Within the relatively short time, it has been in existence, the ISS has actively advanced stereology which is now applied by scientists all over the world in various biological disciplines. Numerous books, publications, computer programmes and applications and dedicated microscopes exist for cost‐effective analysis. Presently, there is no justification for totally descriptive biological studies. With time, novel bias‐free sampling and quantitation techniques have been developed and tested. Mathematicians, statisticians and physical and biological scientists combined their skills to create a new scientific discipline of stereology that allowed for reliable and reproducible quantitation of structural entities of composite physical and biological materials and extrapolation of measurements made on two‐dimensional profiles/images to their three‐dimensional forms. About half a century ago, at an interdisciplinary meeting which was held in Feldberg (Germany), the International Society of Stereology (ISS) was formed. The investigations failed to fully explicate the functional designs of whole organisms and their constituent parts. For a long time, biology was a qualitative (descriptive) science.