This article provides a comprehensive review on nanoparticles and nanostructured materials, focusing on their history, sources, toxicity, and regulations. Nanomaterials (NMs) are defined as materials with dimensions ranging from 1 to 1000 nm, exhibiting unique properties not found in their bulk counterparts. The review discusses the classification of NMs based on their size, composition, shape, and origin, emphasizing the importance of understanding their properties for risk assessment. It highlights the distinction between synthetic (engineered) and naturally occurring NPs and NSMs, noting that both types can have toxic effects on mammalian cells and tissues. The article also addresses the historical development of NMs, from ancient uses by Egyptians and Romans to modern scientific advancements. It covers the sources of NMs, including natural processes like volcanic eruptions and forest fires, as well as human activities such as industrial processes and vehicle emissions. The review also examines the potential health risks associated with NMs, such as oxidative stress and the formation of reactive oxygen species, and discusses the regulations implemented by different countries to mitigate these risks. The article concludes with an overview of the biomedical applications of NMs, including their use in cosmetics, sunscreens, and drug delivery systems, while emphasizing the need for further research on their long-term effects.This article provides a comprehensive review on nanoparticles and nanostructured materials, focusing on their history, sources, toxicity, and regulations. Nanomaterials (NMs) are defined as materials with dimensions ranging from 1 to 1000 nm, exhibiting unique properties not found in their bulk counterparts. The review discusses the classification of NMs based on their size, composition, shape, and origin, emphasizing the importance of understanding their properties for risk assessment. It highlights the distinction between synthetic (engineered) and naturally occurring NPs and NSMs, noting that both types can have toxic effects on mammalian cells and tissues. The article also addresses the historical development of NMs, from ancient uses by Egyptians and Romans to modern scientific advancements. It covers the sources of NMs, including natural processes like volcanic eruptions and forest fires, as well as human activities such as industrial processes and vehicle emissions. The review also examines the potential health risks associated with NMs, such as oxidative stress and the formation of reactive oxygen species, and discusses the regulations implemented by different countries to mitigate these risks. The article concludes with an overview of the biomedical applications of NMs, including their use in cosmetics, sunscreens, and drug delivery systems, while emphasizing the need for further research on their long-term effects.