Lignin structure and its engineering open an alternative feedstock for an industry. Lignin contributes up to 30 wt% of lignocellulosic biomasses. Different methods such as steam explosion, soda process, organosolv, kraft process, lignosulfonates, etc. are used for the isolation of lignin. Methods such as acetylation, alkylation, esterification, etc. are used for the modification of lignin. Lignin gives structural stiffness to the cell wall. Lignin is also used for the preparation of electrochemical capacitors. Lignin and its composite are used for the sensor. In the case of bioimaging, lignin-based carbon quantum dots are used. Other major applications of lignin are reported in drug delivery systems, wastewater treatment, and antimicrobial agents. Thus, lignin has emerged as a potential biomaterial for human welfare in industry.