Lignin is a large phenolic polymer found in the cell wall of most land plants.Volume ABR104, provides in-depth reviews on the most recent discoveries in the field.It revisits the lignin paradigm and reviews the occurrence of unconventional lignin precursors that are derived from both the monolignol biosynthetic pathway, and from other polyphenolic biosynthetic pathways.The volume encompasses the most recent data about the regulation of lignin biosynthesis in a environment of polysaccharides, the importance of oxidases, the pivotal role of feruloylation and coumaroylation of the cell wall both in the lignified stem and in the cereal grain.The volume gives an important part to the transcriptional regulation at different scales.At last, vibrational and fluorescence microscopy methods to characterize the lignin-decorated cell wall as well the most recent bioengineering approaches towards lignin modification are reviewed.