Deep vein thrombosis (DVT) is a medical condition where a blood clot forms in a deep vein, usually in the legs. This can occur due to prolonged inactivity, such as sitting for long periods, or certain medical conditions that affect blood flow. Symptoms may include swelling, pain, and redness in the affected area, but some people may not experience any noticeable signs. If left untreated, DVT can lead to serious complications, such as a pulmonary embolism, where the clot travels to the lungs. Risk factors include age, obesity, and certain medications. Early diagnosis and treatment are essential for preventing complications.