Nanoparticles are extremely small materials that are measured on the nanoscale (1 to 100 nanometers). Nanomedicine utilizes nanoparticles for applications in healthcare and medicine such as targeted drug delivery, diagnostic imaging, and cancer treatment. While nanoparticles show promise for improving medical outcomes, their toxicity must first be established as size and surface area at the nanoscale can impact biological interactions and potentially lead to oxidative stress, inflammation, or accumulation in organs. Continued research seeks to understand and address potential health effects to fully realize the future vision and endless possibilities of nanomedicine for diagnosis, treatment, and repair of human biological systems at the molecular level.