What condition is characterized by the inflammation of a vein?

Phlebitis is the condition characterized by inflammation of a vein, which can occur in superficial veins or deeper venous structures. This inflammation can be caused by various factors, such as injury, infection, or the presence of a blood clot, leading to symptoms like pain, swelling, and redness in the affected area. Understanding phlebitis is vital in the context of vascular health, as it can potentially lead to more serious conditions like thrombus formation, which can complicate treatment and recovery.

Thrombosis refers specifically to the formation of a blood clot within a blood vessel, which can occur in arteries or veins, but it does not inherently include inflammation. Varicose veins are swollen, twisted veins that typically occur in the legs, resulting from inefficiencies in blood flow, rather than inflammation of the vein itself. An aneurysm involves the abnormal bulging or weakening of a blood vessel wall, not inflammation. Therefore, the distinctive feature of phlebitis is the inflammation aspect, making it the correct answer.