Recent studies have clearly shown the importance of polyunsaturated fatty acids (as essential fatty acids) and their nutritional value for human health. In this review, various sources, nutritional properties, and metabolism routes of long‐chain polyunsaturated fatty acids (LC‐PUFA) are introduced. Since the conversion efficiency of linoleic acid (LA) to arachidonic acid (AA) and also α‐linolenic acid (ALA) to docosahexaenoic acid (DHA) and eicosatetraenoic acid (EPA) is low in humans, looking for the numerous sources of AA, EPA and EPA fatty acids. The sources include aquatic (fish, crustaceans, and mollusks), animal sources (meat, egg, and milk), plant sources including 20 plants, most of which were weeds having a good amount ofLC‐PUFA, fruits, herbs, and seeds; cyanobacteria; and microorganisms (bacteria, fungi, microalgae, and diatoms).