People often know about a stroke or about someone affected by a stroke, but not always what constitutes a stroke. A stroke occurs when blood flow to the brain is interrupted or reduced due to a blockage or rupture of a blood vessel or artery that supplies blood to the brain. The interruption of blood flow deprives the brain of necessary nutrients and oxygen, killing surrounding brain cells. There are three main types of stroke: ischemic stroke, hemorrhagic stroke, and transient ischemic stroke. Ischemic strokes occur due to blockage or clotting of a blood vessel or artery. There are two types of ischemic strokes: embolic and thrombotic strokes. An embolic stroke occurs when a blood clot or other substance forms in the body, travels through the bloodstream, and eventually lodges in a small blood vessel or artery supplying blood to the brain. A thrombotic stroke occurs when a blockage forms in one or more arteries in the brain. The second type of stroke, hemorrhagic stroke, is caused by the rupture of a weakened blood vessel. Blood vessels can weaken in two main ways: aneurysm, a bloating of a weak area in a blood vessel, and arteriovenous malformations (AVM), an abnormal connection of arteries to veins. A hemorrhagic stroke can be either an intracerebral stroke, bleeding caused by a blood vessel in the brain, or a subarachnoid stroke, a ruptured aneurysm in a large artery near the membrane surrounding the brain . Finally, transient ischemic attacks are temporary moving clots that cause “miniature” or “warning” strokes. There are many causes of stroke and risk factors that can increase the likelihood of a stroke. Causes include conditions such as atherosclerosis, also known as plaque buildup...... middle of paper ...... and prevention. (December 10, 2013). Stroke Facts. USA.gov. Retrieved January 17, 2014, from http://www.cdc.gov/Stroke/facts.htmAmerican Stroke Association. (October 23, 2012). About the stroke. American Stroke Association. Retrieved January 18, 2014, from http://www.Strokeassociation.org/STROKEORG/AboutStroke/About-Stroke_UCM_308529_SubHomePage.jspNational Stoke Association. (2014). What is a stroke? National Stroke Association. Accessed January 18, 2014, from http://www.Stroke.org/site/PageServer?pagename=StrokeMayo Clinic. (1998). Stroke disease and conditions. Mayo Clinic. Accessed January 19, 2014, from http://www.mayoclinic.org/diseases-conditions/Stroke/basics/treatment/con-20042884University Hospital Newark, New Jersey. (nd). Stroke statistics. University Hospital in Newark, New Jersey. Retrieved January 19, 2014 from http://www.uhnj.org/stroke/stats.htm