A stroke typically occurs when the blood supply to part of the brain is cut off.
It is a serious, life-threatening medical condition which can result in death.
Who is at risk?
According to the NHS, older people are most at risk of having a stroke. However they can occur at any age - including in children.
According to NHS Choices, one of the main symptoms of stroke is when the muscles on one side of the face droop, which results in the person not being able to smile. In some cases, the mouth or eye area might have dropped too.
People experiencing a stroke may not be able to lift both of their arms and keep them there - usually because of arm weakness or numbness.
Additionally their speech may become slurred or "garbled". In some cases, the person may not be able to talk at all despite appearing to be awake.
If you experience any of these symptoms, it is important to act fast and call 999 immediately. Speed is key with treating stroke, and the quicker a person is able to be treated, the less chance there is of permanent damage.
How to prevent stroke
Like many other health complaints, simple changes in lifestyle - including eating healthily and exercising more - can reduce your risk of stroke.
Alice Mackintosh, nutritionist at The Food Doctor said: "Though genetic predisposition plays a part in the development of cardiovascular issues, it has been hypothesized that most cases of stroke can be prevented by living a healthy lifestyle, thereby reducing risks of further compromising heart health.
"Factors that can make one more susceptible to strokes include: smoking, stress, low physical activity, a high saturated fat diet, high cholesterol levels, uncontrolled diabetes and high blood pressure."
Nutritionist Karen Poole says that it's important to add liver-supporting foods into your diet to help regulate cholesterol. These include onions, garlic, cabbage, fennel, broccoli, watercress, celery, radish, rocket, chicory, garlic, artichoke and spinach.
Additionally, cutting down on pastries and fatty meats, consuming plenty of Omega-3 (found in fish such as salmon and mackerel) and stocking up on B12, folic acid and B2, can help lower your risk.