Nowadays, choice is a ubiquitous aspect of everyday life. The emergence of the web has contributed to this explosion of choice, providing a seemingly endless landscape of goods and services to choose from. Whilst choice is held to be fundamental to individual freedom, wellbeing and self-identity, we currently have little understanding about how websites shape or govern choice, and what this might mean for individuals and society. This thesis undertakes a foundational examination of how choice is shaped in online spaces with respect to the design features and architecture of websites. Websites, or parts thereof, that are designed to enable users to navigate choice and compare between options to make decisions, are defined in this study as 'Technologies of Choice' (ToC).In undertaking the study, a phased, mixed methods approach was used. Drawing on several fields of literature, including science and technology studies, Foucaultian social theory, current and emerging social perspectives of choice, and Internet studies, a conceptual framework was developed for examining how choice is constructed and governed on the web. The ToC conceptual framework has four over-arching dimensions: 'Having Choice', 'Facilitating Choice', 'Knowledge Production', and 'Configuring Users'. The conceptual framework was then elaborated through an analysis of websites, resulting in 12 'sub-dimensions' and 56 'features'. The 12 sub-dimensions categorise sets of ToC features that shape choice in particular ways, for example, the 'scale' at which choice is provided or the different 'characteristics of commensurability' that make comparisons possible.Following this, the resulting conceptual framework was applied as an analytical tool to categorise 500 top-ranking websites, using content analysis. Of these 500 websites, 193 (or 39%) were identified as 'ToC websites'. The features of these 193 websites were analysed using descriptive statistics, multiple correspondence analysis, and hierarchical clustering, in order to determine the scale and patterns of distribution of ToC on the web, including whether there are broader 'types' of ToC that shape choice differently. ToC are found to be widespread on the web, constituting a kind of 'infrastructure of modernity'. Whilst ToC are predominantly observed in the commercial settings of recreational services and personal goods, the thesis shows that they are also found in other contexts, including consumer information, health and social care, and in different countries. Although the choice-making literature focuses on comparisons between 'products', the study finds that ToC more commonly enable comparisons between private services (67% of ToC sites) than private goods (42% of ToC sites). Similarly, choice is not always global: a third of ToC websites scale down the options on offer, for example to a particular brand (e.g. Virgin Media or BMW).Despite the ubiquity of ToC, the thesis finds diversity in their design. ToC features are not deployed uniformly on the web: some features are widely used (...