What information is Stored in Alert.log

Oracle's Alert Log [alert_sid.log/alert_(db_name).log] is a text file which can be opened with any text editor. The directory where it is found can be determined by the initialization parameter " background_dump_dest ", it records messages and errors that arise during the day to day database activities.
The messages in the alert log includes:

• Information of Instance Startup and Shutdown
• Errors causing generation of trace files.
• Create, alter and drop SQL statements executed on database, tablespaces and rollback segments.
• Errors arising during a materialized view is refreshed.
• ORA-00600 internal errors.
• Block Corruption (ORA-01578) Errors.
• Dead Locks(ORA-00060) Errors.
• Pointers to error generated trace files and dump files.

The alert log can be deleted and renamed if required for ex: if it reaches certain size, then you can delete or rename the alert log. Oracle will simply create a new alert log and start writing to it. Deleting the alert log or renaming won't affect the database functionality or performance.