The forced oscillation technique (FOT) is a noninvasive method for measuring respiratory mechanics by superimposing small-amplitude pressure oscillations on normal breathing. This technique does not require respiratory maneuvers, making it advantageous over conventional lung function tests. The European Respiratory Society Task Force Report provides guidelines for the application and interpretation of FOT as a routine lung function test in both adult and pediatric populations. FOT data, particularly at lower frequencies, are sensitive to airway obstruction but do not distinguish between obstructive and restrictive lung disorders. There is no consensus on the sensitivity of FOT for bronchodilation testing in adults, but respiratory resistance values have been shown to be sensitive in children. FOT is reliable for assessing bronchial hyperresponsiveness in both adults and children and does not modify airway smooth muscle tone, unlike spirometry. It is also effective in detecting impairments of lung function due to smoking or occupational hazards, making it ideal for epidemiological and field studies. New applications include monitoring respiratory mechanics during mechanical ventilation and sleep. The report covers methodology, potential and limitations, respiratory impedance, measurement arrangements, oscillation frequencies, recommendations for measurements, signal processing, report of results, measurement conditions, clinical applications, reference values, reproducibility, diagnostic capacity, follow-up and field studies, identification of airway reactivity, reversibility, and bronchial hyperresponsiveness.The forced oscillation technique (FOT) is a noninvasive method for measuring respiratory mechanics by superimposing small-amplitude pressure oscillations on normal breathing. This technique does not require respiratory maneuvers, making it advantageous over conventional lung function tests. The European Respiratory Society Task Force Report provides guidelines for the application and interpretation of FOT as a routine lung function test in both adult and pediatric populations. FOT data, particularly at lower frequencies, are sensitive to airway obstruction but do not distinguish between obstructive and restrictive lung disorders. There is no consensus on the sensitivity of FOT for bronchodilation testing in adults, but respiratory resistance values have been shown to be sensitive in children. FOT is reliable for assessing bronchial hyperresponsiveness in both adults and children and does not modify airway smooth muscle tone, unlike spirometry. It is also effective in detecting impairments of lung function due to smoking or occupational hazards, making it ideal for epidemiological and field studies. New applications include monitoring respiratory mechanics during mechanical ventilation and sleep. The report covers methodology, potential and limitations, respiratory impedance, measurement arrangements, oscillation frequencies, recommendations for measurements, signal processing, report of results, measurement conditions, clinical applications, reference values, reproducibility, diagnostic capacity, follow-up and field studies, identification of airway reactivity, reversibility, and bronchial hyperresponsiveness.