This handbook, with its 24 chapters, provides an actual overview of the structure, function, and application of carbohydrate-modifying biocatalysts. Unlike amino acids and nucleic acids, carbohydrates have been disregarded for a long time by the scientific community, mainly due to their complex structure and a lack of suited experimental methods for structure determination. Meanwhile, the situation changed with increasing knowledge about carbohydrates, glycoconjugates, and carbohydrate-modifying enzymes together with the key roles they play in biological processes such as recognition, signal transduction, immune responses, and others.