Lignin, a complex polymer of phenylpropane units, is a crucial component of the cell walls of vascular plants, providing structural integrity, functionality for the transport of water and nutrients, and enhanced resistance to microbial attack. This chapter delves into the intricate structure of lignin, highlighting its diverse chemical composition and exploring the underlying biosynthetic pathways. In addition to structural insights, this chapter explores advanced analytical techniques used to characterize lignin, including, for example, methods based on spectroscopy, chromatography, and mass spectrometry. This chapter also highlights the various industrial, environmental, and biotechnological applications of lignin analysis. Finally, we address current challenges in lignin analysis and propose future directions to advance the field. This comprehensive examination of lignin structure and analytics aims to enhance our understanding and utilization of this vital biopolymer.