Final answer:
Bipolar disorder is a disorder in which a person alternates between periods of mania and depression. It is characterized by dramatic shifts in energy and mood.
Step-by-step explanation:
Bipolar disorder is a disorder in which a person typically alternates between periods of euphoric feelings of mania and periods of depression. It is characterized by dramatic shifts in energy and mood, often affecting the individual's ability to carry out day-to-day tasks. Bipolar disorder used to be called manic depression because of the way people would swing between manic and depressive episodes.