LOG file (.log)
Also known as: .log file, log files, application log, system log
A LOG file (.log) is a plain-text record an app or operating system writes as it runs, logging events, errors, and activity with timestamps. Logs are useful for troubleshooting but can quietly pile up and take significant space over time.
- Plain-text record of events, errors, and activity
- Written automatically as apps and the OS run
- Old logs are usually safe to clear and can free space
What logs are for
A log is a running diary. Each line records something that happened — an app launch, a warning, a failed request — usually with a timestamp. Developers and support teams read logs to figure out why something broke.
Most logs are written automatically in the background and never opened by the average user. They live in places like a Mac’s ~/Library/Logs and system Console, or an app’s own folder.
Do logs take up space?
Individually a log is small, but verbose or long-running apps can accumulate gigabytes of old logs over months. They are a common, overlooked contributor to a full disk and to the System Data category on Apple devices.
Old logs are generally safe to clear — they are diagnostic history, not personal files or settings. Apps recreate them as needed, so deleting stale logs frees space without breaking anything.