The main objective of the seminar is to review the current understanding of lung function growth and decline in healthy populations and those with disease, among both children and adults. The aim is to evaluate factors that account for variation in absolute and normalised data, and in trajectories and trends over time. Finally, the organisers also aim to revise key and controversial concepts, as early COPD and asthma / COPD overlap that are linked to the different vital lung function trajectories.