Slide presented at "What People Leave Behind: Marks, Traces, Footprints and their Significance for Social Sciences", Online, June 15-16, 2021. The digital traces come from two different necessities: technological and social. The technological necessity is the traces used to ensure the proper operation of the system (e.g cookies, IP address). The social necessity is the traces used to facilitate interaction into the platforms (e.g. login, username, posting, liking). Recently the use of digital traces is used in data journalism and OSINT (Open Source Intelligence) a new approach to information in which the knowledge is based on investigation rather than research. The paper aims to introduce this new kind of approach and their contribution to the research in digital sociology.