Reading disabilities can be categorized according to the level of difficulty a person has with decoding printed words. There are three main types of reading disabilities: developmental dyslexia, specific reading disabilities, and functional illiteracy.
Developmental dyslexia is the most common type of reading disability, affecting about 5-7% of the population. People with developmental dyslexia have difficulty decoding and understanding words on a printed page. They usually have difficulty reading from left to right and may have problems with phonemic awareness and word decoding.
Specific reading disabilities are also common, affecting about 2-5% of people. People with specific reading disabilities have significant difficulty with one or more skills necessary to read, such as phonemic awareness, word decoding, and fluency.
Functional illiteracy is the least common type of reading disability, affecting about 1-2% of the population. People with functional illiteracy have difficulty with reading because they have difficulty with basic skills, such as reading speed, comprehension, and fluency.