CAP may begin with upper-respiratory-like symptoms such as sore throat, fatigue, low-grade fever, and cough. In other cases, onset is abrupt with high fever, chills, and productive cough developing quickly. Infection can occur after inhalation of pathogens via respiratory droplets or when normal airway defenses weaken and organisms reach the lung parenchyma. Smoking, recent viral infections, older age, poor nutrition, and immunosuppression reduce protective mechanisms. Operationally, CAP often follows a “quiet start with accelerating trajectory,” with symptoms becoming more pronounced over 48–72 hours. Early evaluation is valuable when respiratory symptoms intensify or systemic signs emerge.