Bipolar disorder is a serious mental condition made up of the following four (4) subtypes:
Bipolar I disorder - this type of bipolar disorder is characterized by cycles of mania lasting at least seven days, and appear with psychotic features, followed by periods of depression that usually last at least two weeks.
Bipolar II disorder - people with bipolar II don't experience mania. Instead, they have periods of extreme depression and hypomania, which is a more mild form of mania.
Cyclothymic disorder - can be classified as a more mild form of bipolar disorder. It consists of mood swings, but the highs and lows are not severe enough to be classified as other types of bipolar.
Bipolar disorder caused by another medical disorder or substance abuse disorder - sometimes bipolar symptoms may not follow patterns, or they can appear due to drug abuse. This form of bipolar disorder is for cases that don't fit into the other categories.