Fibre is the cell of a tree and the main raw material of paper. The most important parts of wood fibre are hemicellulose, cellulose and lignin. Cellulose is the material of the cell wall, which provides the mechanical support needed by the cell. Lignin is a bonding material found in wood, which binds the fibres together and gives them strength. Thus, cellulose and lignin “hold the tree up”.