*Introductory Chapter: Introduction to Structure Properties and Application of Lignin DOI: http://dx.doi.org/10.5772/intechopen.110024*

functionalities present in it. It has been noticed from the literature that lignin-based food packaging helps to protect the food against UV radiation [21]. High potential of lignin is also observed in biofoaming. Foaming in polymers is introduced by blowing air or chemicals between the polymer matrixes. Here, the lignin has found its importance due to polyhydroxyl groups present in it, as it can substitute natural polyols in polyurethane [22]. Resins are the another important sector where lignin has been found replacing phenol in phenol-formaldehyde resins [23].

Considering the tremendous properties of lignin, it has been an interest of researchers to find out its biomedical and pharma applications in form of hydrogels, aerogels, and sensors. Lignin-based hydrogels have been noticed to show good results in tissue engineering and drug delivery applications owing to their porous nature and high swelling capacity in aqueous media [24]. A review article published in 2000 has shown the application of lignin in biosensing [25]. These lignin-based sensors are designed to measure the biological species quantitatively.

Apart from above-mentioned applications, there are still endless applications of lignin molecule. It is really difficult to task to enlist all the applications here. Few such applications are absorption of heavy metals [26], flocullants [27], fibers [28], batteries [29], and much more.
