Changes in the structure, chemistry and bonding at internal interfaces often have a great influence on the properties of materials. High resolution imaging and Energy Dispersive X‐ray Spectroscopy in the Transmission Electron Microscope have been used extensively to study the structure and composition at interfaces. Spatially resolved Electron Energy Loss Spectroscopy (EELS) in the Scanning Transmission Electron Microscope (STEM) offers a new probe to explore the effect of structure and chemistry changes on the local bonding at interfaces. This paper reviews the relationship between EELS and electronic structure and illustrates the insights obtained from this technique with the help of examples which include: a) The effect of B segregation on grain boundaries in Ni3Al and Ni3Si. b) The effect of Bi segregation on grain boundaries in Cu. c) Bonding changes at two metal‐ceramic interfaces :Nb‐Al2O3and Cu‐ A12O3.