Nanoemulsions are advanced drug delivery systems that overcome the limitations of conventional systems. They are thermodynamically stable, isotropic systems with droplet sizes between 20-200 nm, formed by mixing two immiscible liquids with surfactants and co-surfactants. Nanoemulsions offer advantages such as improved bioavailability, non-toxicity, and enhanced physical stability. They can be formulated into various forms like foams, creams, and sprays and are used for drug delivery, enzyme replacement therapy, cancer treatment, and vaccination. Nanoemulsions are classified into three types: oil-in-water, water-in-oil, and bi-continuous. Components include oil, surfactants, and aqueous phases. Surfactants reduce surface tension, stabilize the system, and form monomolecular, multimolecular, or solid particulate films. Preparation methods include high-energy techniques like high-pressure homogenization, ultrasonic emulsification, and microfluidization, as well as low-energy methods like phase inversion temperature and spontaneous emulsification. Characterization involves droplet size analysis, viscosity, drug content, polydispersity, dye test, refractive index, pH, zeta potential, fluorescence test, percentage transmittance, conductance measurement, and filter paper test. Nanoemulsions are stable, transparent, and have uniform droplet sizes. They are used for targeted drug delivery, prolonged action, and masking the taste of oily liquids. They can protect drugs from hydrolysis and oxidation. Nanoemulsions are widely used in pharmaceutical systems and are expected to have further applications in drug delivery and formulation development.Nanoemulsions are advanced drug delivery systems that overcome the limitations of conventional systems. They are thermodynamically stable, isotropic systems with droplet sizes between 20-200 nm, formed by mixing two immiscible liquids with surfactants and co-surfactants. Nanoemulsions offer advantages such as improved bioavailability, non-toxicity, and enhanced physical stability. They can be formulated into various forms like foams, creams, and sprays and are used for drug delivery, enzyme replacement therapy, cancer treatment, and vaccination. Nanoemulsions are classified into three types: oil-in-water, water-in-oil, and bi-continuous. Components include oil, surfactants, and aqueous phases. Surfactants reduce surface tension, stabilize the system, and form monomolecular, multimolecular, or solid particulate films. Preparation methods include high-energy techniques like high-pressure homogenization, ultrasonic emulsification, and microfluidization, as well as low-energy methods like phase inversion temperature and spontaneous emulsification. Characterization involves droplet size analysis, viscosity, drug content, polydispersity, dye test, refractive index, pH, zeta potential, fluorescence test, percentage transmittance, conductance measurement, and filter paper test. Nanoemulsions are stable, transparent, and have uniform droplet sizes. They are used for targeted drug delivery, prolonged action, and masking the taste of oily liquids. They can protect drugs from hydrolysis and oxidation. Nanoemulsions are widely used in pharmaceutical systems and are expected to have further applications in drug delivery and formulation development.