The term ‘silk’ makes almost all of us think first of lustrous and shimmery fabrics. This chapter discusses in brief the history of the evolution of silk from China and how silks spread to the rest of the world. It describes the different types of mulberry and non-mulberry silkworm species, their habits and habitats. This chapter briefly describes silk protein sericins (glue proteins) and fibroins produced by different silkworms as well as silk protein encoding genes. It also outlines the different diseases of silkworms and, finally, different applications of silk proteins in the core fields of biomedical engineering.