Lipids, one of the major natural products, usually have high biocompatibility and low toxicity. Due to their
proper physicochemical properties, they are the most commonly used materials for building modern drug delivery systems,
especially nanocarriers. However, to impart new functions or to satisfy special requirements, the lipids can be modified
or synthesized. Using lipids or lipid derivatives, various lipid-based drug or gene delivery systems have been developed
and show potential in pre-clinical and clinical applications. In this article, the most commonly used lipids are discussed
in terms of their properties and functions as drug carrier components, their chemical modifications, the formulation
or composition of lipid-based nanocarriers, and their biomedical applications. This article provides a critical view and
possible future directions of lipid-based drug delivery strategies.