Nanoparticles have emerged as a promising tool in drug delivery systems due to their ability to enhance the pharmacokinetic and pharmacodynamic properties of various drug molecules. This review discusses the formulation, characterization, and applications of nanoparticles in drug delivery, emphasizing their potential for targeted delivery and controlled release. Nanoparticles, defined as particles in the range of 10-1000 nm, can be prepared using various methods such as dispersion of preformed polymers, polymerization of monomers, and coacervation. They offer advantages such as increased stability, controlled release, and the ability to target specific sites in the body. However, challenges such as particle aggregation and limited drug loading remain to be addressed before clinical application. Nanoparticles can be functionalized with targeting ligands or coated with hydrophilic polymers to enhance their circulation time and reduce opsonization. The size and surface properties of nanoparticles significantly influence their biodistribution, toxicity, and drug delivery efficiency. Smaller nanoparticles have a higher surface area, leading to faster drug release, while larger particles can encapsulate more drug and release it more slowly. The surface charge and hydrophilicity of nanoparticles also affect their interaction with the immune system and their ability to cross biological barriers such as the blood-brain barrier. Nanoparticles have shown promise in various applications, including tumor targeting, gene delivery, and oral delivery of peptides and proteins. They can be used to deliver drugs to specific tissues or cells, reducing side effects and improving therapeutic efficacy. However, challenges such as rapid clearance by the mononuclear phagocytic system and the need for efficient drug loading and release mechanisms must be overcome for clinical success. Despite these challenges, nanoparticles represent a significant advancement in drug delivery technology, offering a versatile platform for targeted and controlled drug delivery.Nanoparticles have emerged as a promising tool in drug delivery systems due to their ability to enhance the pharmacokinetic and pharmacodynamic properties of various drug molecules. This review discusses the formulation, characterization, and applications of nanoparticles in drug delivery, emphasizing their potential for targeted delivery and controlled release. Nanoparticles, defined as particles in the range of 10-1000 nm, can be prepared using various methods such as dispersion of preformed polymers, polymerization of monomers, and coacervation. They offer advantages such as increased stability, controlled release, and the ability to target specific sites in the body. However, challenges such as particle aggregation and limited drug loading remain to be addressed before clinical application. Nanoparticles can be functionalized with targeting ligands or coated with hydrophilic polymers to enhance their circulation time and reduce opsonization. The size and surface properties of nanoparticles significantly influence their biodistribution, toxicity, and drug delivery efficiency. Smaller nanoparticles have a higher surface area, leading to faster drug release, while larger particles can encapsulate more drug and release it more slowly. The surface charge and hydrophilicity of nanoparticles also affect their interaction with the immune system and their ability to cross biological barriers such as the blood-brain barrier. Nanoparticles have shown promise in various applications, including tumor targeting, gene delivery, and oral delivery of peptides and proteins. They can be used to deliver drugs to specific tissues or cells, reducing side effects and improving therapeutic efficacy. However, challenges such as rapid clearance by the mononuclear phagocytic system and the need for efficient drug loading and release mechanisms must be overcome for clinical success. Despite these challenges, nanoparticles represent a significant advancement in drug delivery technology, offering a versatile platform for targeted and controlled drug delivery.