Visual images proliferate within educational contexts and are accessible across a range of media: in print, via the Web, as part of learning resources and in multimedia software. The increased ease of access to images has been mirrored by an increase in their use by academics. However, it is evident from the literature that there is a need for more research into how to make the best use of images within learning and teaching resources. The word 'image' is, in a sense, deceptive. A little thought illustrates that there are a significant number of different types of 'images' or pictorial/graphical representations. This paper distils out the key features that emerge from the research findings and map these to relevant pedagogical theories. The presentation attempts to define different image types in order to make the ways in which they can be used to support learning and teaching more transparent. Furthermore, a better understanding and categorisation of digital images will help to facilitate the integration of image resources with pedagogical practice.