In a hyper connected world, online communities shape our lives in both visible and invisible ways. This short book from the ÉCHOS DU QUOTIDIEN collection (Publisher : Five Minutes) explores how digital spaces transform work, learning, activism and personal identity. Drawing on recent studies (2024 2025), it reveals the strengths of borderless collaboration while highlighting risks of polarisation, cyberhate and addiction. You will learn how communities of practice stimulate innovation, how health forums and support networks foster well being, and how movements such as #YesAllWomen or #1000BlackGirlBooks reinvent civic mobilisation. The author also analyses the rise of de influencing, the growth of hybrid work and interventions against digital addiction, while offering concrete paths to build responsible and inclusive communities. This critical and engaged panorama invites you to become aware of your role as a netizen and to act for a more ethical, more human internet. Take ten minutes to change how you see networks !