The adoption of artificial intelligence, data science, data analytics, among other techniques is predominant in many contexts and domains: often used to help us decide which items to buy, what music to listen to, and in high-stakes domains such as education, healthcare provision or criminal justice, among others. The performance of such AI systems depends both on the learning algorithms, as well as the data used for their training and evaluation. The role of the algorithms is well studied. In contrast, research that focuses on the data used in AI systems is not commonplace. Data, however, is always at their core, being a crucial component for advancing and assessing the technological field.