"Near-Field Scanning Optical Microscopy: Chemical Imaging" by Bogdan Dragnea is a chapter in the third edition of the Dekker Encyclopedia of Nanoscience and Nanotechnology, published in 2011 by CRC Press. This chapter delves into the principles and applications of Near-Field Scanning Optical Microscopy (NSOM) for chemical imaging. NSOM is a technique that surpasses the diffraction limit of traditional optical microscopy, enabling imaging with spatial resolutions down to tens of nanometers. This high resolution is achieved by scanning a sharp probe very close to the sample's surface, collecting optical signals from the near-field region. The chapter discusses how NSOM can be integrated with various spectroscopic methods, such as infrared and Raman spectroscopy, to obtain detailed chemical information at the nanoscale. It also highlights the technique's applications in fields like materials science and biology, where understanding chemical composition at high spatial resolution is crucial.