Portal hypertension occurs when hepatic venous pressure gradient exceeds 10 mm Hg and risk of variceal bleeding increases above 12 mm Hg. It can be caused by prehepatic issues like portal vein thrombosis, intrahepatic issues like cirrhosis, or post-hepatic issues like Budd-Chiari syndrome. Clinical signs include splenomegaly, ascites, collateral veins, and risk of gastrointestinal bleeding from esophageal varices. Management involves beta-blocker therapy to reduce pressure, antibiotics and endoscopic therapy for acute bleeding, and TIPSS or shunting for refractory cases. Complications include variceal bleeding, ascites, and hypersplenism.