Simple definition
A filesystem journal records pending metadata operations to improve consistency after unexpected shutdowns.
Purpose and use
A filesystem journal helps restore consistency after an abrupt interruption.
How does it work?
Operations are recorded before commitment; guarantees for metadata and file data depend on the filesystem and operating mode.
Example and verification
After an incident, review storage errors and filesystem state rather than assuming every file is intact.
Points to watch
Journaling is not a backup and does not guarantee recovery of deleted files or every recent write.
In short
A journal improves crash consistency without replacing data protection.