Omega-3 refers to a family of polyunsaturated fatty acids with their first double bond at the third carbon from the methyl end, comprising alpha-linolenic acid (ALA) from plants and the long-chain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from marine sources. EPA and DHA support heart health by moderating triglycerides and inflammation, DHA is a structural component of brain and retinal membranes, and adequate intake is linked to healthier pregnancy outcomes. Oily fish is the richest source; walnuts, flaxseed, and rapeseed oil supply ALA, though conversion to EPA and DHA in the body is inefficient. Supplements, functional foods, and enriched eggs extend intake options. Public health guidance generally recommends one to two portions of oily fish weekly, balancing benefits against contaminant and sustainability concerns.