Cyanobacteria (CB), also called Cyanophyta (or Blue-green algae) are ancient (3.5 billion years old) procaryotic microorganisms known to be related to the chloroplasts of all green plants, with CB evolving oxygenic photosynthesis over two billion years ago. CB are thought to have made a major contribution to the formation of the earth's atmosphere and are still forming almost half present-day oxygen. CB also contribute to the formation of sedimentary rock (carbonates in the marine littorals and freshwater springs). Among other important processes in the lithosphere, CB can colonize bare rock and be essential for rock weathering.

CB are found worldwide, although some taxa (genera, species, ecomorphs) are characteristic of particular environments from polar to tropical and cold to hot. In freshwaters their niches range from those forming nuisance blooms to those in the cleanest springs and mountain streams, where they often reach their highest diversity. No doubt many taxa still remain to be described.

Nowadays molecular methods are helping to make clear the natural (phylogenetic) relationships of their taxa and also habitat preferences related to differing gene expression based on both single molecular markers and whole genome analyses.

The IAC Symposium 2016 intends to offer a suitable platform to bridge classical and recent understanding of their morphology, ultrastructure and ecology with functional molecular biology.