Sphingolipids are a structurally diverse class of lipids found in all eukaryotes and several bacteria and are emerging as a particularly rich source of bioactive molecules. Functions of sphingolipids range from structural roles to signal transduction mediators that affect the regulation of cancer cell growth, differentiation, senescence, apoptosis, proliferation, inflammation, and cell motility. The number of molecular species of sphingolipids found in cells is astounding with diversification at three different positions within the sphingolipid molecule (the long-chain base, the long or very long chain acyl group and the head group). This combinatorial-like diversification suggests that a specific sphingolipid (that is, one with a defined long chain base, N-linked acyl chain and head group) may be required for each of the diverse functions of the class of sphingolipids.