This Book is a platform to convey essential concepts of Solid lipid nanoparticles, a colloidal nano drug delivery system. Solid Lipid nanoparticles, known as SLNs This promising drug carrier system is at the interface in the preexisting lipid systems (emulsions and liposomes) and polymeric nanoparticle systems. These concepts can be employed to develop advanced Solid lipid nanoparticles for a range of biomedical applications. This book explains the advantages, dis advantages preparation methods, characterization of SLNs. The applications of SLNs in various fields are explained. It also explains the targeted drug delivery through SLNs. The concept of PEG coating on SLN is also explained.This book has become an important reference source for scientists, teachers, doctors, research scholars, and university students, who are interested in the field.