Due to filesystem permission restrictions and PHP Safe Mode restrictions. For all users to utilize the Joomla! installers an FTP layer exists to handle filesystem manipulation.

Enter an FTP username and password with access to the Joomla! root directory, this will be the FTP account that handles all filesystem operations when Joomla! requires FTP access to complete a task.

For security reasons, it is best if a separate FTP user account is created with access only to the Joomla! installation.