Alginate has been widely investigated since it was first isolated and described in 1881 by Stanford (E.C.C Stanford, 1881) and has since become a vastly utilised polymer with a variety of applications. Alginate is not only exploited in the food industry, but also in the paper and textile industries, pharmaceutical and more recently, for biomedical applications. The versatility of alginate has led to it being a fairly well understood material and has been subject to a great number of systematic rheological investigations, information from which has been subsequently utilised in food applications. More recently, their “high value” pharmaceutical and biomedical applications have driven the development and understanding of alginate further. This chapter intends to provide a brief overview of the chemical properties of alginates and to review the influence of molecular structure on the physical, functional and more specifically, rheological properties which are exploited in food systems. Specific applications in foods are also covered which highlight the multi functional nature of alginate and its future potential.