Since their introduction on the market, earlier than 1980s, a large number of biodegradable polymers have been synthesized  with the major objective of developing polymeric systems with stable electrical and mechanical properties during their programmed service life. In particular, biodegradable polymers are of great interest since these biomaterials are able to break down and be catabolized after use, eventually in carbon dioxide and water, by microoganisms under natural environment. Biodegradable polymers can be classified into different categories depending on the synthesis and on the sources, such as agro- or natural polymers that consist of lignocellulosic products, polysaccharides, and others . Biopolymers fall into the natural polymers category, and represent one of the hot topics of polymer research. They are useful in medicine, agriculture, drug release, and packaging fields. In this chapter, the most important terrestrial biopolymers are reviewed in terms of source, properties, blending with other biodegradable polymers, and applications.