Technological innovations have occurred throughout history and rapidly increased over the modern age. New technologies are developed and co-exist with the old before supplanting them. Transport offers several examples; from sailing to steam ships to automobiles replacing horse-based transportation. Technological transitions (TT) describe how these technological innovations occur and are incorporated into society. Alongside the technological developments TT considers wider societal changes such as "user practices, regulation, industrial networks (supply, production, distribution), infrastructure, and symbolic meaning or culture". For a technology to have use, it must be linked to social structures human agency and organisations to fulfil a specific need. Hughes refers to the 'seamless web' where physical artefacts, organisations, scientific communities, and social practices combine. A technological system includes technical and non-technical aspects, and it a major shift in the socio-technical configurations (involving at least one new technology) is when a technological transition occurs.
Work on technological transitions draws on a number of fields including history of science, technology studies, and evolutionary economics. The focus of evolutionary economics is on economic change, but as a driver of this technological change has been considered in the literature. Joseph Schumpeter, in his classic Theory of Economic Development placed the emphasis on non-economic forces as the driver for growth. The human actor, the entrepreneur is seen as the cause of economic development which occurs as a cyclical process. Schumpeter proposed that radical innovations were the catalyst for Kondratiev cycles.
The Russian economist Kondratiev proposed that economic growth operated in boom and bust cycles of approximately 50 year periods. These cycles were characterised by periods of expansion, stagnation and recession. The period of expansion is associated with the introduction of a new technology, e.g. steam power or the microprocessor. At the time of publication, Kondratiev had considered that two cycles had occurred in the nineteenth century and third was beginning at the turn of the twentieth. Modern writers, such as Freeman and Perez outlined five cycles in the modern age:
Freeman and Perez proposed that each cycle consists of pervasive technologies, their production and economic structures that support them. Termed 'techno-economic paradigms', they suggest that the shift from one paradigm to another is the result of emergent new technologies.
Following the recent economic crisis, authors such as Moody and Nogrady have suggested that a new cycle is emerging from the old, centred on the use of sustainable technologies in a resource depleted world.
Thomas Kuhn described how a paradigm shift is a wholesale shift in the basic understanding of a scientific theory. Examples in science include the change of thought from miasma to germ theory as a cause of disease. Building on this work, Giovanni Dosi developed the concept of 'technical paradigms' and 'technological trajectories'. In considering how engineers work, the technical paradigm is an outlook on the technological problem, a definition of what the problems and solutions are. It charts the idea of specific progress. By identifying the problems to be solved the paradigm exerts an influence on technological change. The pattern of problem solving activity and the direction of progress is the technological trajectory. In similar fashion, Nelson and Winter (,)defined the concept of the 'technological regime' which directs technological change through the beliefs of engineers of what problems to solve. The work of the actors and organisations is the result of organisational and cognitive routines which determines search behaviour. This places boundaries and also trajectories (direction) to those boundaries.
In analysing (historic) cases of technological transitions researchers from the systems in transition branch of transitions research have used a multi-level perspective (MLP) as a heuristic model to understand changes in socio-technical systems. () Innovation system approaches traditionally focus on the production side. A socio-technical approach combines the science and technology in devising a production, with the application of the technology in fulfilling a societal function. Linking the two domains are the distribution, infrastructure and markets of the product. This approach considers a transition to be multi-dimensional as technology is only one aspect.
The MLP proposes three analytical levels: the niche, regime and landscape.
Niche (Micro-level) Radical innovations occur at the niche level. These act as 'safe havens' for fledgling technologies to develop, largely free from market pressures which occur at the regime level. The US Military has acted as niche for major twentieth century technologies such as the aircraft, radio and the internet. More recently, California's Silicon Valley has provided an arena for ICT focused technologies to emerge. Some innovations will challenge the existing regime while others fail.
Regime (Meso-level) The socio-technical regime, as defined by Geels, includes a web of inter-linking actors across different social groups and communities following a set of rules. In effect, the established practices of a given system. Seven dimensions have been identified in the socio-technical regime: technology, user practices and application, the symbolic meaning of technology, infrastructure, policy and techno-scientific knowledge. Change does occur at the regime level but it is normally slow and incremental unlike the radical change at the niche level. The actors who constitute the existing regime are set to gain from perpetuating the incumbent technology at the expense of the new. This is known as 'lock-in'.
Landscape (Macro-level) Exogenous to the previous levels is the socio-technical landscape. A broad range of factors are contained here, such as economic pressures, cultural values, social trends, wars and environmental issues. Change occurs at an even slower rate than at the regime level.
A transition is said to happen when a regime shift has occurred. This is the result of the interplay between the three levels. Regimes are relatively inert and resistant to change being structured to incremental innovation following established trajectories. As such, transitions are difficult to achieve. The current regime is typically suffering internal issues. Pressure from the landscape level may cause 'cracks' or 'windows of opportunity' through which innovations at the niche level may initially co-exist with the established technology before achieving ascendency. Once the technology has fully embedded into society the transition is said to be completed.
The MLP has been used in describing a range of historic transitions in socio-technical regimes for mobility, sanitation, food, lighting and so on. While early research focused on historical transitions, a second strand of research was more focused on transitions to sustainable technologies in key sectors such as transport, energy and housing.
Geels  presented three historical transitions on system innovation relating to modes of transportation. The technological transition from sailing ships to steamships in the UK will be summarised and shown in the context of a wider system innovation.
Great Britain was the world's leading naval power in the nineteenth century, and led the way in the transition from sail to steam. At first, the introduction of steam technology co-existed with the current regime. Steam tugs assisted sail ships into port and hybrid steam / sail ships appeared. Landscape developments create the necessity for improvements in the technology. A demand for trans-Atlantic emigration was prompted by the Irish potato famine, European political instability and the lure of gold in California. The requirement for such arduous journeys had prompted a wealth of innovations at the niche level in steamship-development. From the late 1880s, as steamship technology improved and costs dropped, the new technology was widely diffused and a new regime established. The changes go beyond a technological transition as it involved new ship management and fleet management practices, new supporting infrastructures and new functionalities.
The nature of transitions varies and the differing qualities result in multiple pathways occurring. Geels and Schot  defined five transition paths:
Transitions are co-evolutionary and multi-dimensional Technological developments occur intertwined with societal needs, wants and uses. A technology is adopted and diffused based on this interplay between innovation and societal requirements. Co-evolution has different aspects. As well as the co-evolution of technology and society, aspects between science, technology, users and culture have been considered.
Multi-actors are involved Scientific and engineering communities are central to the development of a technology, but a wide range of actors are involved in a transition. This can include organisations, policy-makers, government, NGOs, special interest groups and others.
Transitions occur at multiple levels As shown in the MLP transitions occur through the interplay of processes at different levels.
Transitions are a long-term process Complete system-change takes time and can be decades in the making. Case studies show them to be between 40 and 90 years.
Transitions are radical For a true transition to occur the technology has to be a radical innovation.
Change is Non-linear The rate of change will vary over time. For example, the pace of change may be slow at the gestation period (at the niche level) but much more rapid when a breakthrough is occurring.
Diffusion of an innovation is the concept of how it is picked up by society, at what rate and why. Everett (1962).The diffusion of a technological innovation into society can be considered in distinct phases. Pre-development is the gestation period where the new technology has yet to make an impact. Take-off is when the process of a system shift is beginning. A breakthrough is occurring when fundamental changes are occurring in existing structures through the interplay of economic, social and cultural forces. Once the rate of change has decreased and a new balance is achieved, stabilization is said to have occurred. A full transition involves an overhaul of existing rules and change of beliefs which takes time, typically spanning at least a generation. This process can be speeded-up through seismic, unforeseen events such as war or economic strife.
Geels proposed a similar four phased approach which draws on the multi-level perspective (MLP) developed by Dutch scholars. Phases one sees the emergence of a novelty, born from the existing regime. Development then occurs in the niche level at phase two. As before, breakthrough then occurs at phase three. In the parlance of the MLP the new technology, having been developed at the niche level, is in competition with the established regime. To breakthrough and achieve wide diffusion, external factors - 'windows of opportunity' are required.
A number of possible circumstances can act as windows of opportunity for the diffusion of new technologies:
Alongside external influences, internal drivers catalyse diffusion. These include economic factors such as the price performance ration. Socio-technical perspectives focus on the links between disparate social and technological elements. Following the breakthrough, the final phases see the new technology supersede the old.
The study of technological transitions has an impact beyond academic interest. The transitions referred to in the literature may relate to historic processes, such as the transportation transitions studied by Geels, but system changes are required to achieve a safe transition to a low carbon-economy. (). Current structural problems are apparent in a range of sectors. Dependency on oil is problematic in the energy sector due to availability, access and contribution to greenhouse gas (GHG) emissions. Transportation is a major user of energy causing significant emission of GHGs. Food production will need to keep pace with an ever-growing world population while overcoming challenges presented by global warming and transportation issues. Incremental change has provided some improvements but a more radical transition is required to achieve a more sustainable future.
Developed from the work on technological transitions is the field of transition management. Within this is an attempt to shape the direction of change complex socio-technical systems to more sustainable patterns. Whereas work on technological transitions is largely based on historic processes, proponents of transition management seek to actively steer transitions in progress.
Genus and Coles outlined a number of criticisms against the analysis of technological transitions, in particular when using the MLP. Empirical research on technological transitions occurring now has been limited, with the focus on historic transitions. Depending on the perspective on transition case studies they could be presented as having occurred on a different transition path to what was shown. For example, the bicycle could be considered an intermediate transport technology between the horse and the car. Judged from shorter different time-frame this could appear a transition in its own right. Determining the nature of a transition is problematic; when it started and ended, or whether one occurred in the sense of a radical innovation displacing an existing socio-technical regime. The perception of time casts doubt on whether a transition has occurred. If viewed over a long enough period even inert regimes may demonstrate radical change in the end. The MLP has also been criticised by scholars studying sustainability transitions using Social Practice Theories.