For effective drug delivery using inhalation route, it is important to use the inhalers correctly. This open-label study will evaluate the error rates during the use of ELLIPTA DPI, alone or in combination, in comparison with other DPIs. The study aims to provide clinical evidence in subjects with COPD that the reduced number of steps required to use the ELLIPTA DPI could result in fewer errors made by subjects, and therefore a more consistent treatment. Approximately 450 subjects prescribed with either of RELVAR® ELLIPTA, ANORO® ELLIPTA, INCRUSE® ELLIPTA, SYMBICORT® TURBUHALER®, SERETIDE® DISKUS®, SPIRIVA® HANDIHALER®, ULTIBRO® BREEZHALER® or SEEBRI® BREEZHALER will be included in the study and will have 2 clinical visits. At Visit 1, subjects will take their maintenance DPIs and the critical and overall errors made by subjects will be assessed. After the assessment, subjects will be instructed on correct use or informed of their correct use of their DPIs. The total duration of the study is approximately 6 weeks. ELLIPTA, SERETIDE and DISKUS are registered trademarks of the GSK group of companies. SYMBICORT and TURBUHALER are registered trademarks of the AstraZeneca group of companies. SPIRIVA and HANDIHALER are registered trademarks of Boehringer Ingelheim Pharmaceuticals. ULTIBRO, BREEZHALER and SEEBRI are registered trademarks of the Novartis group of companies.