There has been considerable interest in drug delivery research over the past few decades using Particulate delivery systems as carriers of small and large molecules. Particulate structures such as nanoparticles have been used as a physical tool to modify and improve the pharmacokinetic and pharmacodynamic properties of different types of drug molecules. They were used in-vivo to Protect the drug entity in the systemic circulation, restrict the drug's access to the selected locations, and deliver the drug to the site of action at a controlled and sustained rate. Different carriers have been used to increase therapeutic benefit in the formulation of nanoparticles for drug delivery research, while minimizing side effects. Here we review different aspects of the formulation of nanoparticles, their characterization, their effects and their applications in the delivery of drug molecules.