Summary: Chronic obstructive pulmonary disease (COPD) is a disease that can be different in each individual. Persistent airflow limitation, which is its permanent feature, can be caused by a mixture of small airway disease (chronic bronchitis) or parenchymal destruction (emphysema). Some patients are characterized by a large number of exacerbations and comorbidities, which leads to rapid disease progress. These pathology and pathophysiology features underlie the selection of the phenotypes of the disease. The differential in cell count of induced sputum, the number of peripheral blood eosinophils, as well as other markers that indicate chronic bacterial colonization can also be helpful in characterizing the endotypes of the disease. Better patient characterization allows us to choose optimal therapeutic options, which reduces the severity of symptoms, and first of all the number of exacerbations and, consequently, the progression of the disease, and to avoid side effects of ineffective drugs.