The document provides an overview of the common cold, a viral infection of the upper respiratory tract, detailing its symptoms, risk factors, transmission methods, and treatment options. Key symptoms evolve over several days, and the average duration of the illness is 3 to 7 days, with potential airway reactivity changes lasting up to 4 weeks. Treatment options include decongestants, humidified air, and pain relievers, with a note on the limited effect of vitamin C.