Quantum dots (QDs) have emerged as a crucial component of the development of advanced photonic devices due to their unique electronic and optical properties originated from quantum confinement effects. The small-size nanoparticles (typically 2–10 nm) lead to quantized energy states that significantly affect their light absorption and emission compared to bulk material. Electrons and holes are confined in all three spatial dimensions, leading to size-dependent energy levels. This property allows for tunable band gaps by simply adjusting the size of the QDs. QDs can absorb and emit light at specific wavelengths, which are tunable based on their size. Larger dots emit longer wavelengths (redder light), while smaller dots emit shorter wavelengths (bluer light). Recent advancements in QDs research have opened numerous applications, including its use in electronics, photonics, advanced sensors, biomedical devices, next-generation energy storage systems, and high-resolution screens. This chapter offers a comprehensive review of the properties and photonics applications of QDs. It also examines future directions for developing and integrating quantum dots in emerging technologies. This will be a valuable resource for researchers, engineers, and industry professionals to understand the basics and diverse applications of QDs.