Nanoscience and nanotechnology is continuously moving forward enabling the precise, controlled fabrication of structures and devices at atomic and molecular scales. Quantum dots are typically semiconductor nanocrystals that have gained tremendous attention due to their unique electronic, magnetic, chemical and optical properties. They have proven very useful in applications in many fields across the physical, engineering, chemical, biological and medical sciences. In this book, tha authors give an overview of the progress and major research developments in the field of quantum dots over the past two decades. They specifically focus on discussing the cutting-edge applications in the fields of information technology, electronics, biotechnology, energy, medicine, cellular imaging and diagnostic bio-sensing. © 2012 by Nova Science Publishers, Inc. All rights reserved.