Carbon Quantum Dots (CQDs/QDs) are nano sized, light emitting spherical particles with unique structural and functional properties. Presently, QDs are highly being used as the new class of fluorescent marker due to its distinctive electronic and imaging properties, high quality signaling, photo bleaching resistance, etc. Due to the aforementioned properties QDs are one of the most researched nanoparticles which can be used for both imaging and therapeutic purpose. Furthermore high selectivity, flexibility, solidity, and capability to penetrate various cells and organelles allows QDs in imaging and targeting the delivery of cancer therapeutics. However, despite all advantages QDs suffers major roadblocks due to poor biocompatibility, toxicity and aggregation of particles. Thus in this article we have reviewed the structural anatomy of QDs, various methods of synthesis, applications of QDs and various roadblocks of using QDs in living tissues.