The literature of humin is reviewed. Humin is described chemically as having a significant aliphatic nature that is probably attributable to the lipids that comprise a significant portion of its organic components. The humic component of humin consists of aromatic and carbohydrate carbon, with an aliphatic component less significant than the corresponding humic acid or fulvic acid isolated from the same sample. Based on NMR relaxation time measurements, the aliphatic carbon and aromatic/carbohydrate carbons seem to represent distinct domains that may represent the different sorption domains of humin described in several recent contaminant sorption models. Several possible areas requiring further research are identified for future study of the environmental chemistry and geochemistry of this material.