Bigender is a non-binary gender identity in with someone has two distinct gender identities. They could feel both genders at the same time or be fluid between them- in which case they may also identify as genderfluid. The two genders can be male and female, (and this is what most people assume bigender means) however bigender can be a combination of any two genders, including non-binary genders. For example, a bigender person could be female and neutrois.
Bigender people may also identify as transgender or non-binary. People who experience more than two genders can be trigender, quadgender, or multigender.