Aphasia is a language disorder that affects how a person communicates, including their speech, writing, and understanding of both spoken and written language. It is caused by damage to the language centers of the brain, usually in the left side of the brain, that control understanding, speaking, and using signed languages. The most common cause of aphasia is brain damage resulting from a stroke, but it can also be caused by a head injury, brain tumor, or a progressive neurological disease. The severity of aphasia depends on a number of things, including the cause and the extent of the brain damage. People with aphasia may have different strengths and weaknesses in their speech patterns, and these patterns are sometimes labeled as different types of aphasia. Some common symptoms of aphasia include difficulty speaking, understanding others, finding words, and reading or writing. There is no medicine for aphasia, but speech and language therapy can help improve communication skills.