Acute worsenings of chronic obstructive pulmonary disease (COPD) were for a long time regarded as transient deteriorations, although occasionally life-threatening. No connection to disease progression was recognized. Data emerging during the last decade showed that patients had a considerably worse survival outcome after severe exacerbations. This insight was consolidated in 2012 by a large population-based cohort analysis. At present, severe exacerbations are regarded as key risk factors for COPD disease progression. The present article summarises the current knowledge on exacerbations of COPD, as delineated during an expert workshop in February 2017. It comprises pathogenic mechanisms, exacerbation triggers, the characteristics of frequent exacerbators, and the predictors of worse survival outcome. The role of comorbidities is considered more closely. The presentation of the pharmacotherapy of acute exacerbation is supplemented by an overview of ventilatory support. Finally, pharmacological and nonpharmacological preventive measures are summarised.