Weird glitch

So earlier today, I got this extremely weird error. Can anyone explain it? I couldn't access the site at all and the only way I could was looking at the cached version of the page. Here is the error message:
An exception occurred: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2) in /var/www/vhosts/www.shadygamer.com/httpdocs/library/Zend/Db/Adapter/Mysqli.php on line 333

Zend_Db_Adapter_Mysqli->_connect() in Zend/Db/Adapter/Abstract.php at line 315
Zend_Db_Adapter_Abstract->getConnection() in XenForo/Application.php at line 553
XenForo_Application->loadDb()
call_user_func_array() in XenForo/Application.php at line 780
XenForo_Application->lazyLoad() in XenForo/Application.php at line 810
XenForo_Application::get() in XenForo/Application.php at line 1099
XenForo_Application::getDb() in XenForo/Error.php at line 47
XenForo_Error::unexpectedException() in XenForo/Application.php at line 295
XenForo_Application::handleException()
Can anyone tell me why this happened? Can anyone explain what this means?

 

It means we had an issue with our MySQL server and it had to be fixed server-side. Nothing on your end that could've been done.

Also, we have a dedicated thread for technical questions: http://boards.theforce.net/threads/post-technical-questions-and-issues-here.50003162/