Quantum dots (Qdots) are nanoscale semiconductor materials with unique optical and electronic properties due to quantum confinement effects. This review discusses the structure, properties, synthesis, and applications of Qdots, focusing on their multimodal uses in optoelectronics, solar cells, and biological imaging. Qdots exhibit size-dependent band gaps and optical absorption/emission properties, allowing tunable luminescence. Their properties are influenced by factors such as size, shape, doping, alloying, and surface passivation. Qdots can be synthesized using top-down or bottom-up methods, with surface passivation techniques like organic or inorganic coatings improving their stability and performance. Applications include electroluminescence devices, solar cells, and bioimaging, where Qdots offer advantages such as high quantum yield, tunable emission, and compatibility with biological systems. The review also covers the effects of doping, alloying, and multi-shell structures on Qdot properties, as well as characterization techniques like TEM, XPS, and EELS. Theoretical models, including the effective mass approximation and linear combination of atomic orbitals, are used to predict Qdot behavior. Overall, Qdots hold significant potential for various technological applications due to their unique optical and electronic properties.Quantum dots (Qdots) are nanoscale semiconductor materials with unique optical and electronic properties due to quantum confinement effects. This review discusses the structure, properties, synthesis, and applications of Qdots, focusing on their multimodal uses in optoelectronics, solar cells, and biological imaging. Qdots exhibit size-dependent band gaps and optical absorption/emission properties, allowing tunable luminescence. Their properties are influenced by factors such as size, shape, doping, alloying, and surface passivation. Qdots can be synthesized using top-down or bottom-up methods, with surface passivation techniques like organic or inorganic coatings improving their stability and performance. Applications include electroluminescence devices, solar cells, and bioimaging, where Qdots offer advantages such as high quantum yield, tunable emission, and compatibility with biological systems. The review also covers the effects of doping, alloying, and multi-shell structures on Qdot properties, as well as characterization techniques like TEM, XPS, and EELS. Theoretical models, including the effective mass approximation and linear combination of atomic orbitals, are used to predict Qdot behavior. Overall, Qdots hold significant potential for various technological applications due to their unique optical and electronic properties.