A Same-sex relationship can take one of several forms, from romantic and sexual, to non-romantic close relationships between two persons of the same sex. The term same-sex relationship may be used when the sexual orientation of participants in a same-sex relationship is not known. As bisexual or pansexual people may participate in same-sex relationships, some activists claim that referring to a same-sex relationship as a "gay relationship" or a "lesbian relationship" is a form of bisexual erasure. The term same-sex marriage is used similarly.