Formulation of poorly soluble drugs has become an intractable problem in the Pharmaceutical field. The research efforts of many researchers, industries, and academic groups have resulted that the solution for this lies in reduction of particle size. Thereafter, many particle size reduction techniques have emerged. Among them, nanosizing of particles or nanotechnology has become a rapidly increasing drug delivery technique. Not only nanotechnology has played a tremendous role in Pharmaceutical and Medical sciences, but also in many other fields. This work aims at exploring and compiling information regarding nanotechnology, its types, preparation modules, toxicity and challenges and their applications. Researchers, academicians, students will be benefitted from this work.