Glycans are among the most complex biological molecules found in nature, being composed of monosaccharide units in various combinations and linkages, and featuring diverse and asymmetric types of branching. Until the 1970s, glycan structures were generally represented in scientific publications as chemically accurate drawings, or using standard IUPAC-approved abbreviations (Sharon 1986; McNaught 1997; Chester 1998). However, given the complexity of many glycan structures, it became difficult to represent such molecules in publication figures, especially those involving multistep biosynthetic pathways or multiple structures. Thus, various investigators began to use symbols to represent monosaccharides in glycans. In 1978, Kornfeld and colleagues put forward an elegant and simple system for representation of vertebrate glycans (Kornfeld et al. 1978), and it entered into popular use over the next two decades. This system was eventually adopted and standardized by the editors of the first edition of the textbook Essentials of Glycobiology (Varki et al. 1999).