There are about 12 million blind people in the United States. They are male and female, of all ages. What they all have in common is that their vision cannot be corrected and their vision makes it more difficult to do major life activities such as driving, etc. This can also be called visual impairment.
Legal blindness is defined in several ways.
This means that this person sees at 20 feet that a normally sighted person can see at 200 feet. Many people have this condition and it can be fixed with glasses. A person who is blind in this way has vision cannot be corrected with glasses. This means that a person cannot see the whole scene as a normally sighted person can. This is measured in degrees.