Lignocellulose has three main constituents, cellulose, hemicellulose, and lignin. Lignin is an abundant bioderived, aromatic, renewable feedstock and a by-product of pulp and paper industry. Presently, only 1 of lignin is utilized for the production of valuable chemicals and other biofuels, while most part of lignin is burnt for heat and power generation. Lignin is such a reliable and sustainable feedstock, which has much more complex structure containing various types of functional groups that can play a major role in modification of lignin. This chapter highlights historical background, chemical composition, and its structure that can prove to be an excellent feedstock, offering the development of high level of technologies for the production of value-added chemicals, biofuels, and composites in future. © 2017 Elsevier Ltd. All rights reserved.