COVID-19 is an infectious respiratory illness caused by the novel coronavirus SARS-CoV-2, first identified in 2019 and responsible for a global pandemic. It spreads primarily through respiratory droplets and aerosols released when an infected person coughs, speaks, or breathes, particularly in indoor or poorly ventilated spaces. Symptoms range from mild cold-like illness to severe pneumonia and may include fever, cough, fatigue, shortness of breath, and loss of taste or smell. While many individuals recover without complications, older adults and those with underlying health conditions are at higher risk for severe disease. Prevention strategies include vaccination, good ventilation, hygiene measures, and staying home when ill, and although the acute emergency phase has passed in many regions, COVID-19 continues to circulate worldwide.