The carbon fiber industry is significantly growing and will continue to grow steeply, but the cost of precursors hinders its full exploitation in industry. Lignin is an aromatic polymer with a high carbon content. It is sustainable and renewable. The main extraction processes of lignin are Kraft pulping, soda pulping, sulfite pulping, organosolv pulping, and dilute acid pulping. The conversion of lignin into carbon fibers involves steps like spinning, which include melt spinning, solution spinning, and electrospinning. The spun precursor fiber is stabilized and finally carbonized. Thus, a carbon fiber with moderate mechanical properties was obtained.