The post-lunch session at the 2019 AoIR Flashpoint Symposium starts with Christina Neumayer and Luca Rossi, who are interested in invisibilities in social media data. For instance, studying protest movements through social media means studying only what is visible about these movements in specific social media platforms – the data must exist in the various technological layers of these platforms in the first place, and those layers significantly constrict what data are available to the researcher. Additionally, such data must also be perceived as meaningful; this requires a shared understanding in the scholarly community that such data can be used …