Abstract-Previous strategic analyses of the field of ICT for sustainability (ICT4S) have often underplayed the role of ICTs in linking large numbers of people, in shaping and transferring ideas, and also the range of sustainability effects that ICTs can cause.The Digital Taxonomy for Sustainability (digitaltaxonomy.com) was developed to address this, through a qualitative analysis of over 500 ICT4S company descriptions. It classifies a digital system (software, hardware or social machine) by the digital "means" it employs and the sustainability "ends" it achieves. The possibilities are mapped out with two component taxonomies. The Sustainability Taxonomy identifies around 20 possible sustainability effects of a digital system, such as the sustainable use of natural resources. The Digital Taxonomy identifies over 80 genres of digital system organised onto a matrix. The rows distinguish how the increasing power of digital systems (the digital capabilities) can be applied to the various stages necessary for achieving change, the change processes that form the columns of the matrix. The indirect change processes (assessing, innovating, and adopting) develop and propagate ideas or things to cause the effects, whilst the driving change process acts to cause the effects directly. The digital capabilities are the three ways ICTs can engage with people to drive change: for artificial capability, the ICT provides the action automatically; for augmented capability, the ICT guides them, to inform and influence their behaviour; and for collective capability, the ICT connects them with others, developing networks that link supply and demand. The rapid development and proliferation of ICTs is increasing the power of all three capabilities. This systematic mapping out of the structure of the industry and the field may help stakeholders coordinate, raise external awareness, and inform the development of theory. In particular, it helps identify opportunities for new and better ICT4S systems.