Research over the last decade has substantially advanced our understanding of cellular redox chemistry and introduced new terms to redox signaling and biological redox switches. It emerges that redox switching affects a plethora of biological processes and seems to be necessary to counterbalance oxidative stress and guarantee cellular survival in oxidative conditions. Despite intensive studies, the mechanisms of redox switching and its consequences are poorly understood, which points towards an extremely complex nature of these phenomena. Indeed, in contrast to classical signalling cascades, cellular redox signaling seems to affect the whole cellular redox environment and a large number of different redox switches. A majority of biological redox switches rely on the oxidation of thiol group(s) of cysteine residue(s); however, thiolates also bind transition metal ions like Zn(II), Cu(I), and iron, and these metal-thiolate motifs also function as redox switches. It follows that a deeper understanding of redox signalling and redox switches could be achieved by a multidisciplinary approach combining advances in the redox chemistry of sulphur, the chemistry of reactive oxygen and nitrogen species, as well as the bioinorganic chemistry of metal complexes. Many of these aspects are reviewed in the current forum issue on biological redox switches with the aim to promote the understanding of cellular redox phenomena at system biology level.