text: Purely illiterate persons can not read or write in any capacity , for all practical purposes . In contrast , functionally illiterate persons can read and possibly write simple sentences with a limited vocabulary , but can not read or write well enough to deal with the everyday requirements of life in their own society .
simplified: That way , a person who is functionally illiterate may be able to write their name , but it is very difficult for them to write more than a few sentences .