Aphasia is a communication disorder that impedes a person’s ability to speak and understand others. It is most commonly caused by brain injury (especially after a stroke), but it may also be caused by head trauma, brain tumors, or infections.

The severity of aphasia ranges from a mild inability to speak, read, or write to nearly no ability to communicate with others. How it affects those afflicted with the disorder is determined by which part of the brain is damaged and what caused the damage.