Literacy is the ability to use the symbols of a writing system.
It is the ability to interpret what the information symbols represent, and to be able to re-create those same symbols so that others can derive the same meaning. Illiteracy is the inability to derive meaning from the symbols used in a writing system. Dyslexia refers to a cognitive difficulty with reading and writing.
It is defined as brain-based type of learning disability that specifically impairs a person's ability to read.