VPN providers can potentially collect several types of data about your usage:
- Connection logs — timestamps of when you connected and disconnected, which server you used, your real IP address, and how much data you transferred
- Activity logs — the websites you visited, files you downloaded, and services you used while connected. This is the most invasive type
- Aggregate logs — anonymized statistics like total bandwidth used per server, number of simultaneous connections. These are generally harmless
A true no-logs VPN stores none of the first two categories. There should be no way to trace any internet activity back to a specific user.