Essential oils are concentrated liquids of complex mixtures of volatile compounds and can be extracted from several plant organs. The use of essential oils as the natural additives for the shelf-life extension of food products is gaining attention due to the risk in using synthetic preservatives. Essential oils can be incorporated into packaging to provide multifunctions, termed “active or smart packaging.” Those essential oils are able to modify the matrix of packaging materials, thereby rendering the improved properties. This review covers up-to-date literatures on essential oils including sources, chemical composition, extraction methods, bioactivities, and their applications, with the emphasis on preservation and the shelf-life extension of food products. CLICK here for complete article. Journal of Food Science, Volume 79, Issue 7, July 2014, Pages R1231–R1249.