ABSTRACT
The term symbiosis was coined by Frank in 1877 and was described by Anton de Bary (1879) as living together of two different organisms in a permanent or long lasting association. On the basis of how each partner is benefi ted in the association, three broad categories of symbiotic relationships are recognized, i.e. commensalism, parasitism and mutualism. In commensalism, one member is helped and the other member is neither helped nor harmed. In parasitism one partner is benefi ted and the other partner is harmed. In mutualism both partners help each other. Symbiotic relationships encompass all major groups of living world. There is a great variation in the size of individuals that take part in the symbiotic association. The terminology in describing symbiotic relationships has now been defi ned by the International Society of Endocytobiology (Schenk, https://www. endocytobiology.org). In relation to cyanobacteria, the terms cyanobiont, cyanelle and cyanome need to be elaborated. A cyanobiont is defi ned as a cyanobacterial partner in a symbiotic relationship. Cyanelle is a genetically autonomous symbiotic endophyte. Cyanome is a symbiotic consortium of host and intracellular cyanobacterium.
