The growing consumer interest in proactive health management is fueling the development of novel functional ingredients and foods. These products go beyond basic nutrition, offering demonstrably positive effects on health. This book defines functional foods and explores the exciting world of emerging functional ingredients. It highlights innovative sources such as upcycled food byproducts (e.g., citrus peels, apple pomace), marine-derived components (e.g., seaweeds, microalgae), and even cultivated microorganisms (e.g., prebiotics).