An error log is a log of errors encountered by a system. There are a number of different ways in which error logs can be used, and they can be extremely useful tools for people who need to diagnose and manage systems such as web servers, office networks, and so forth. Accessing the error log may require special administrative permissions which are designed as a security measure to prevent unauthorized people from seeing documentation of errors.
Some error logs list every single error which occurs. Others may be programmed to selectively save information about errors, listing only certain error codes. However the system work, each entry in the error log includes an error code, a time, and may add other information such as an action someone was trying to complete, someone's location, and whether or not the error was resolved. The logs can be searched to identify specific patterns or errors encountered by a particular user.
For webmasters, checking error logs can provide useful information about problems people are encountering. People do not always report errors, and if a webmaster has a bad link, a form which can't submit, or a similar problem, it may show up on the log before someone brings the webmaster's attention to the problem. The logs can also provide information about hacking attempts, as hackers may cause errors on the server while they attempt to compromise the system.
For systems like office networks, logs are used to keep track of problems encountered by users and to try and determine what causes these errors. An error log on an individual system or piece of equipment can also be useful, especially if someone reports problems. By viewing the log, a technician can get more information about the problems encountered and what, exactly, happened. The technician can resolve the error or provide the user with information about where he or she went wrong.
Some systems will maintain an error log up to a certain number of entries, while others archive logs so they can be consulted at any time. It may also be possible to adjust these settings inside the control panel of the system. Someone launching a new website, for example, might want a large archive, anticipating potential problems when the site goes live, while a site which is stable and well established might not need to have such an extensive archive.