Embolism is the obstruction of a blood vessel by a foreign body, such as a blood clot (thrombus), air bubble, or fat globule, that travels through the bloodstream. It is clinically significant as it can lead to tissue ischemia, organ dysfunction, or infarction, depending on the location of the blockage. A common example is pulmonary embolism, where a clot travels to the lungs, causing respiratory distress and potential cardiovascular collapse.