This review of literature investigates existing user research relating to the UK’s Gallery, Library, Archive and Museum (GLAM) digital collections. Over the last 30 years, the number of online collections, and the number of online visitors using those collections, has increased significantly. Although the use of collections has been on the rise, whether it is meaningful in terms of audience engagement, understanding and appreciation is still questionable, particularly in relation to accurate user behavioural data. A proper understanding of who and how visitors use digital collections is critical for the success of the UK’s galleries, libraries, archives and museums in the information age. This review looks at available work from 2015 to 2021 to compare ways in which users have been categorised, their behaviours and identify areas where further discussion is required. Within the date range; 2015-2021, there is limited material on what characterise user categories leading Rees and Vitale (2020) to state: “Actual profiles of potential audiences are thin on the ground” (2020, p. 9). While a range of work on digital audiences exist, in-depth empirical research does appear to have slowed since 2015. There has been a focus within the GLAM sector on quantitative reporting which lacks detail and nuance in terms of audience behaviours. This leads to a lack of richer and deeper understanding of digital users.