Microneedles, first conceptualized for drug delivery decades ago, became a focus of research in the mid-1990s with advances in microfabrication. They enable drug and vaccine delivery through various mechanisms: solid microneedles for skin pretreatment, drug-coated microneedles for controlled release, dissolving microneedles for drug encapsulation, and hollow microneedles for infusion. Microneedles have been used to deliver a wide range of drugs, biotherapeutics, and vaccines, including human studies. Influenza vaccination using hollow microneedles is widely used, and solid microneedles are sold for cosmetic purposes. Microneedles have also been adapted for eye and cellular delivery. Successful application depends on device function, skin recovery, drug stability, and patient outcomes. Microneedles are poised to advance into clinical practice for better therapies and applications. Microneedles are fabricated from various materials, including silicon, metal, polymer, glass, and ceramic, using techniques like photolithography, laser cutting, and electroplating. Solid microneedles are used for skin pretreatment, drug-coated microneedles for controlled release, dissolving microneedles for drug encapsulation, and hollow microneedles for infusion. Microneedles have been used for skin pretreatment, drug delivery, vaccine delivery, and intracellular delivery. They have been shown to increase skin permeability and enable the delivery of low molecular weight drugs, biotherapeutics, and vaccines. Microneedles have been used for insulin delivery, vaccine delivery, and other biotherapeutics. They have also been used for skin pretreatment with microneedles to enhance vaccine delivery and for intracellular delivery. Microneedles have been used for skin pretreatment with microneedles to enhance vaccine delivery and for intracellular delivery. They have been used for skin pretreatment with microneedles to enhance vaccine delivery and for intracellular delivery. Microneedles have been used for skin pretreatment with microneedles to enhance vaccine delivery and for intracellular delivery.Microneedles, first conceptualized for drug delivery decades ago, became a focus of research in the mid-1990s with advances in microfabrication. They enable drug and vaccine delivery through various mechanisms: solid microneedles for skin pretreatment, drug-coated microneedles for controlled release, dissolving microneedles for drug encapsulation, and hollow microneedles for infusion. Microneedles have been used to deliver a wide range of drugs, biotherapeutics, and vaccines, including human studies. Influenza vaccination using hollow microneedles is widely used, and solid microneedles are sold for cosmetic purposes. Microneedles have also been adapted for eye and cellular delivery. Successful application depends on device function, skin recovery, drug stability, and patient outcomes. Microneedles are poised to advance into clinical practice for better therapies and applications. Microneedles are fabricated from various materials, including silicon, metal, polymer, glass, and ceramic, using techniques like photolithography, laser cutting, and electroplating. Solid microneedles are used for skin pretreatment, drug-coated microneedles for controlled release, dissolving microneedles for drug encapsulation, and hollow microneedles for infusion. Microneedles have been used for skin pretreatment, drug delivery, vaccine delivery, and intracellular delivery. They have been shown to increase skin permeability and enable the delivery of low molecular weight drugs, biotherapeutics, and vaccines. Microneedles have been used for insulin delivery, vaccine delivery, and other biotherapeutics. They have also been used for skin pretreatment with microneedles to enhance vaccine delivery and for intracellular delivery. Microneedles have been used for skin pretreatment with microneedles to enhance vaccine delivery and for intracellular delivery. They have been used for skin pretreatment with microneedles to enhance vaccine delivery and for intracellular delivery. Microneedles have been used for skin pretreatment with microneedles to enhance vaccine delivery and for intracellular delivery.