An embolism is the obstruction of a blood vessel by an embolus, which can be a thrombus, fat globule, air bubble, or foreign material, potentially leading to serious health issues like stroke or sudden death. Diagnosis and treatment vary based on the cause and location of the embolism, with options including embolectomy, thrombolysis, and lifestyle changes to reduce risk factors. Preventive measures include maintaining a healthy diet, exercising, quitting smoking, and managing health conditions such as high blood pressure and cholesterol.