This article presents results obtained from electron microscope images and the structural information they can give. The chemical and physical properties of the phases as well as the conditions for their formation, though very important points in this research program, are outside the scope of this article. A brief description of the phenomenon called crystallographic shear is presented since this is the important feature in reduced tungsten oxides and many other oxide systems that have been investigated by this technique. A discussion of the experimental conditions for obtaining structure images concludes the article.