As a spatial concept, density is a useful tool in predicting and controlling land use. However, policymakers, practitioners, academics and citizens are often uncertain about how density, and especially higher densities, can be best utilised to create and nurture the design of urban environments. Barriers related to definitions, calculations, concepts and correlations with relevant issues prevent people from understanding density beyond a simple ratio of units to area. More needs to be done to show that density plays a key role in planning, architecture and urban design, and that discussions of density cannot be done in isolation of a whole host issues found in the built and natural environment. To that end, this paper aims to clarify some of the issues surrounding density, particularly about available definitions, calculating terms, the advantages and disadvantages of increasing densities in cities and uncovering relationships between density and issues pertinent to the design of urban environments. With these relationships in mind, a new way of visualising density is then offered—through a taxonomy of density—that categorises density into its component parts, allowing scholars, policymakers and practitioners to understand what aspects of density have been examined and what gaps are still present. Finally, a re-conceptualisation of density is presented, illustrating that density is more than a quantitative calculation that exists on its own; rather, for density to be considered as an integral part of the urban environment, both ‘hard’ (i.e., quantitative) and ‘soft’ (i.e., qualitative, contextual) elements must be included.