Lymphedema is a chronic condition characterized by the accumulation of lymphatic fluid in tissues, leading to persistent swelling, most commonly in the arms or legs. It occurs when the lymphatic system—responsible for draining excess fluid and supporting immune function—is damaged or obstructed. Lymphedema may be primary (due to congenital or genetic abnormalities of the lymphatic vessels) or secondary, often resulting from surgery, radiation therapy, infection, trauma, or cancer treatment that affects lymph nodes. Symptoms include swelling, heaviness, tightness of the skin, reduced range of motion, and increased susceptibility to skin infections. Over time, untreated lymphedema can lead to thickened skin and tissue changes, making early recognition important for long-term management.