The article reviews the recent trends and potential applications of synthesizing nanoparticles using biological entities, such as microorganisms, plants, and other biological systems. It highlights the advantages of green chemistry-based techniques in producing nanoparticles without the use of harsh, toxic, and expensive chemicals. The review covers various methods for characterizing nanoparticles, including spectroscopy and microscopy techniques. It also discusses the synthesis of metal and metal oxide nanoparticles using microbial routes, the use of plant extracts, and the factors influencing the synthesis process. The article emphasizes the potential of biological synthesis in creating nanoparticles with well-defined properties and their applications in biomedical, catalytic, and optoelectronic fields. The biological synthesis of nanoparticles using plants is particularly noted for its simplicity, cost-effectiveness, and scalability. The review concludes by discussing the synthesis of specific nanoparticles, such as gold, silver, copper, palladium, and platinum, using various plant extracts and the resulting properties and applications.The article reviews the recent trends and potential applications of synthesizing nanoparticles using biological entities, such as microorganisms, plants, and other biological systems. It highlights the advantages of green chemistry-based techniques in producing nanoparticles without the use of harsh, toxic, and expensive chemicals. The review covers various methods for characterizing nanoparticles, including spectroscopy and microscopy techniques. It also discusses the synthesis of metal and metal oxide nanoparticles using microbial routes, the use of plant extracts, and the factors influencing the synthesis process. The article emphasizes the potential of biological synthesis in creating nanoparticles with well-defined properties and their applications in biomedical, catalytic, and optoelectronic fields. The biological synthesis of nanoparticles using plants is particularly noted for its simplicity, cost-effectiveness, and scalability. The review concludes by discussing the synthesis of specific nanoparticles, such as gold, silver, copper, palladium, and platinum, using various plant extracts and the resulting properties and applications.