Xdebug is a PHP extension that greatly simplifies the debugging process. Once installed and enabled, Xdebug generates easier to read error messages that include a backtrace. Xdebug also allows you to step through the life cycle of a Drupal page request in incredibly useful ways.
- Improve the formatting of error messages output to the browser
- Connect an IDE to allow setting breakpoints and inspecting the request lifecycle
- Enable and examine an application profile to find inefficiencies
Xdebug is a PHP Extension. Generally speaking, it is installed and configured once per server. Once you set it up on your local development server you likely won't have to make any configuration changes at all.