Bipolar disorder used to be known as manic depression. It's a serious illness, one that can lead to risky behavior, damaged relationships and careers, even suicidal tendencies -- if it's not treated.
Bipolar disorder is characterized by extreme changes in mood (poles) -- from mania to depression. Between these mood swings, a person with Bipolar disorder may experience normal moods.
"Manic" describes an increasingly restless, energetic, talkative, reckless, powerful, euphoric period. Lavish spending sprees or impulsive risky sex can be irresistible. Then, at some point, this high-flying mood can spiral into something darker -- irritation, confusion, anger, feeling trapped.