Respiratory illness refers to a broad range of conditions that affect the airways and lungs, impairing the body’s ability to breathe efficiently and exchange oxygen. These illnesses may be caused by viruses, bacteria, allergens, environmental irritants, or chronic inflammatory processes. Common examples include the common cold, influenza, bronchitis, pneumonia, asthma, and chronic obstructive pulmonary disease (COPD). Symptoms often include cough, shortness of breath, wheezing, chest tightness, congestion, fever, or fatigue. Respiratory illnesses can be acute and short-term or chronic and progressive, depending on the underlying cause. Because breathing is essential for overall health, persistent or worsening respiratory symptoms should be medically evaluated.