A stroke is an interruption to the blood supply to the brain.
The brain is the most complex organ in the body. It regulates everything your body does - breathing, moving, speaking, your thoughts and feelings, sleeping and waking to name a few.
Like any other organ in the body the brain needs a constant supply of blood to provide it with oxygen and nutrients for the brain cells to work. If the brain cells are deprived of oxygen and other nutrients they get damaged and die. Unlike other cells in the body, once brain cells die they cannot regrow