"The DSM-IV organizes each psychiatric diagnosis into five levels (axes) relating to different aspects of disorder or disability:

Axis I: clinical disorders, including major mental disorders, as well as developmental and learning disorders

Common Axis I disorders include depression, anxiety disorders, bipolar disorder, ADHD, Autism, phobias, and schizophrenia."

http://en.wikipedia.org/wiki/Diagnostic_and_Statistical_Manu...