(also log file)
A computer-generated file recording events, such as online activities, system errors, or user communication. Logs are helpful to determine why a device or app has crashed, but they can also reveal a lot of sensitive information about the user.
Real log examples
Windows: Windows devices automatically generate crash logs when they shut down unexpectedly, revealing the circumstances and your actions at the time of the crash.
Messenger: Messenger creates chat logs of all your conversations and stores them on Meta servers. Your chat history can then be viewed online or downloaded to your device.