From Mac Guides
The Console is a utility that comes with Mac OS X that displays log files. Viewing logs can help troubleshoot various problems.
The Console is located at /Applications/Utilities/Console.
The Console can display a number of different log files, each listed in the Log List.
- console.log - Information outputted by applications, usually errors of some kind.
- system.log - Information about system events, such as sleep and wake events.
- ~/Library/Logs - Various logs related to the current user. The most useful of these is the CrashReporter logs, which contain information about application crashes. These logs can help to troubleshoot crashes, and, if sent to application developers, can help to fix these bugs.
- /Library/Logs - Various logs related to the system. Generally less useful than the other logs.
- /var/logs - Various low level logs. Also of little use in most circumstances.