What are (event) logs and how do logs work?

A log is a documentation of (IT) changes, e.g. when applications were updated or when incorrect login attempts occurred. They are usually stored automatically in so-called log files.

All changes to IT systems should be logged so that they can be traced later. In particular, individual identifiers should be used to ensure that they cannot be falsified. Automated logs or a manual change log can be used for this purpose.