Dyspnea is a medical term that refers to the sensation of shortness of breath or difficulty breathing. It can occur during physical activity or at rest and may be caused by various conditions, including asthma, chronic obstructive pulmonary disease (COPD), or heart failure. People experiencing dyspnea may feel a tightness in their chest, rapid breathing, or a sense of suffocation. It is important to identify the underlying cause to provide appropriate treatment, which may include medications, oxygen therapy, or lifestyle changes to improve respiratory function.