The document provides important notes on changes to data sources and calculations in the 2021 Global Digital Report. It notes that internet user numbers no longer include data from social media platforms, and as a result may appear lower than previous reports. Social media user numbers also may not represent unique individuals. Comparability advisories are included throughout to indicate where data is not comparable to previous reports. The document aims to provide the most accurate information while separating relevant data sources to allow for more informed analysis.