A forthcoming issue of Current Opinion in Biotechnology features a set of reviews on the topic of lignin, particularly its chemistry and applications. Lignin is a complex set of polymers that provide structural support to vascular plants (See Renault et al. for insights into lignin’s evolutionary origins). From a biochemical perspective, lignin is interesting because the polymerization of its monomers occurs non-enzymatically (see Perkins et al.; Tobimatsu and Schuetz; and Terette and Dupree). As a consequence, lignin is hugely diverse, with structural properties that vary with its species and site of origin (see Barbosa et al.). Lignin is also industrially very important. Although indepsensible for the strength of wood, it gets in the way of the production of other plant-derived materials. For example, lignin must be removed to isolate cabohydrate-based cell walls for pulp, paper and biofuel production. However, the extracted lignin itself can be used for energy production and as a source for biopolymers and nanomaterials (see Grossman and Vermerris; and Kamimura et al.). Efforts are also underway to further our understanding of lignin synthesis and function in planta, in part with the objective to alter lignin production in planta for enhanced biofuel production and improved digestibility of forage for animals (See Ohtani and Demura; Vanholme et al.; Mahon and Manfield; and Barros et al.). This is a super collection of articles featuring this very special polymer. (Summary by Mary Williams) Curr. Opin. Biotechnol. April 2019.