Pleural effusion is a common clinical condition characterized by the accumulation of excess fluid within the pleural space due to disruption of normal pleural fluid dynamics. The etiology is diverse and includes systemic conditions such as congestive heart failure, liver cirrhosis, and renal disease, as well as localized pleural pathologies including infection, malignancy, and inflammatory disorders. Accurate classification of pleural effusion into transudative and exudative types, primarily using biochemical parameters such as Light's criteria, remains the cornerstone of diagnostic evaluation and guides subsequent clinical management.