Optical properties of quantum dots have created a lot of interest within the community due to their size tunable, fundamentally unique properties arising from the quantum confinement effect that are unforeseen in bulk. In this review we have highlighted some of the recent advances in the field including the synthetic challenges and advances to control not only the size but also their shape, internal structure and their coupling with the neighbouring nanocrystals leading to exciting new optical properties. We have further explored the various optical techniques that have been used to understand the electronic structure of not only ensemble and temporally averaged nanostructures but also with temporal resolution as well as single particle microscopy and hence understand the unique size dependent properties. We then explore a few of the unique properties or specialized class of nanocrystals using a combination of various optical properties. The different classes of nanocrystals discussed in this review include materials such as transition metal doped nanocrystals as well as infrared emitting materials. The fundamentally unique processes such as blinking, that is observed in almost all single molecule nanocrystals, or ultrafast processes occurring in these nanocrystals that determine the properties of these materials have also been discussed. The review concludes with a brief discussion on the current and potential applications and a brief outlook for the future of this field.