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 tightness in the chest, increased effort to breathe, or a sense of suffocation. It is important to identify the underlying cause of dyspnea, as it can indicate serious health issues that may require medical attention or treatment.