According to the United States Center for Disease control's page of Attention-Deficit/Hyperactivity Disorder (ADHD) the diagnostic criteria (DSM-IV) are separated into two categories: inattention and impulsive behavior.
If at least six of the listed symptoms of either category "have been present for at least 6 months to a point that is disruptive and inappropriate for developmental level" then the person in question is identified as having ADHD. If the majority of the symptoms are from the "inattention" category the condition is "ADHD predominately inattentive type", if from "Hyperactivity/Impulsivity" then "Predominately Hyperactive-impulsive type" and if it's a fairly equal combination of the two it's "Combined type" ADHD.
Oh, you want some examples and quotes do ye? Too busy to visit our friends at the CDC? Ok fine. Here are some excerpts.
Symptoms of ADHDInattention
- Often does not give close attention to details or makes careless mistakes in schoolwork, work, or other activities.
- Often has trouble keeping attention on tasks or play activities.
- Often does not seem to listen when spoken to directly.
- Often does not follow instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions).
- Often has trouble organizing activities.
- Often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long period of time (such as schoolwork or homework).
- Often loses things needed for tasks and activities (e.g. toys, school assignments, pencils, books, or tools).
- Is often easily distracted.
- Often fidgets with hands or feet or squirms in seat.
- Often gets up from seat when remaining in seat is expected.
- Often runs about or climbs when and where it is not appropriate (adolescents or adults may feel very restless).
- Often has trouble playing or enjoying leisure activities quietly.
- Is often "on the go" or often acts as if "driven by a motor".
- Often talks excessively.
- Often blurts out answers before questions have been finished.
- Often has trouble waiting one's turn.
- Often interrupts or intrudes on others (e.g., butts into conversations or games).
- Some symptoms that cause impairment were present before age 7 years.
- Some impairment from the symptoms is present in two or more settings (e.g. at school/work and at home).
- There must be clear evidence of significant impairment in social, school, or work functioning.
- The symptoms do not happen only during the course of a Pervasive Developmental Disorder, Schizophrenia, or other Psychotic Disorder. The symptoms are not better accounted for by another mental disorder (e.g. Mood Disorder, Anxiety Disorder, Dissociative Disorder, or a Personality Disorder).
Research suggests that children with difficulty in their peer relationships, for example, being rejected by peers or not having a close friends. [...] Parents of children with ADHD may be less likely to report that their child plays with groups of friends or is involved in after-school activities, and half as likely to report that their child has many good friends. Parents of children with ADHD may be more than twice as likely than other parents to report that their child is picked on at school or has trouble getting along with other children.
(PS. Apologies to the GREAT Bill Watterson for using his art.)