Seaweeds are considered as usual foods, novel feed ingredients, nutraceutical compounds, and source of pigments (R-phycoerythrin, fucoxanthin, lutein etc.) and proteins. They appear to possess bioactive properties, such as hypolipidemic, antioxidant, and immune-stimulative actions; furthermore, their proteins are considered just as nutritious as terrestrial vegetables. Seaweeds of major importance are quite numerous, such as Gracilaria gracilis, Mastocarpus stellatus, Sargassum cristaefolium etc. They provide pigments and colorants from different chemical classes (chlorophylls, phycobiliproteins, carotenoids etc). Working with fresh or dried biomasses is an open question, together with the use of novel techniques for extraction (ultrasonication, green extraction using edible oils). Practical aspects such as cooking of seaweeds before consumption by humans in order to increase pigment bioaccessibility or other nutritional aspects is also presented in this book chapter.