The book on "Phytochemicals" is a broad-spectrum topic and will contain all those topics that will provide a good insight into plant-based bioactive compounds produced by plants such as polyphenols, carotenoids, phytosterols, isoprenoids, saponins, bioactive peptides, dietary fibres, etc. This book will resume the current research in the field of phytochemicals, starting from their composition and classification to their role in plants, foods, and humans. The wide range of topics may include their chemistry, extraction, applications in the food and pharmaceutical industry, functionalities, various health aspects, and importantly - sustainability. Currently, the world is facing global warming and a shortage of resources to feed human beings. The plants could not only provide beneficial phytochemicals to fight against many diseases and health disorders but also fulfil their dietary needs as an alternative source to animal food. The scientists working on the different aspects of phytochemicals are welcome to submit their valuable contributions to this book.