Bipolar disorder is a mental illness characterized by extreme shifts in mood between mania and depression. It has been documented since ancient times but was classified as its own disorder in the 19th century. There are two main types, Bipolar 1 and 2, distinguished by the severity of manic episodes. While the exact causes are unknown, genetics and environmental factors are believed to play a role. Around 5-6% of people will experience bipolar disorder in their lifetime. With treatment including medication and therapy, many people are able to effectively manage the disorder and live fulfilling lives.