Error Log File
A log that monitor traffic and indicate errors that have been generated as visitors access your Web site.
Common errors include: file does not exist (a link to your site is no longer working), send aborted (visitor aborted a download of a file because it was too large and slow), file stopped transferring (a server or connection problem), abandoned shopping cart file (shows that purchase process was not completed).
Reviewing logs periodically is important after the launch of your Web site.