One of the main advantages of scanning transmission electron microscopy (STEM) is the capability of recording a number of signals at the location of the electron beam, including characteristic X-rays and the measurement of the distribution of energy lost by the primary electron beam. Due to their importance in materials research, the use of these two techniques, known in general as “analytical electron microscopy,” has been the topic of extended reviews and monographs (Botton 2008, Joy et al. 1986, Sigle 2005, Williams and Carter 1996). In general these techniques are used, primarily, to extract local information on the composition of the sample with a resolution limited in part by the delocalization of the signal due to the long-range interaction discussed in 10.1007/978-1-4419-7200-2_6 of this book and in part by the broadening of the beam due to the sample thickness. In this chapter, we will focus on the particular subset of analytical signals that allow the extraction of information on the chemical environment of the atoms probed by the fast primary electron beam. Such information is mainly provided in STEM by Energy Loss Near Edge Structures.